Physiology 
and Hygiene 



jlount 




Glass. 
Book. 



Copyright^ 



.10 



COPYRIGHT DEPOSIT. 



PHYSIOLOGY AND HYGIENE 



A TEXT-BOOK AND MANUAL 

FOR 

HIGH SCHOOLS 



BY 

RALPH EARL BLOUNT, A.B. 
Teacher in the Waller High S< hool, Chicago. Illinois 




CHI NEW YORK 

ROW, PETERSON AND COMPANY 



.Br 



Copyright, 1914 
ROW, PETERSON & COMPANY 



OCT I 1914 



'CI.A379821 



PREFACE 

This book is written for pupils between twelve and 
sixteen years of age. With the minimum quantity of 
laboratory work called for in the text, the course can 
be finished in ten weeks. If a class can spend a half 
year on the subject, the text will be adequate for a reci- 
tation guide. The work should be supplemented by the 
study of a variety of animals to illustrate the several 
physiological processes in organisms less complex than 
the human. For example, the short sketch of respira- 
tion on page 108 should be expanded to several days' 
laboratory work. The comparative study of the blood 
systems of the animal groups, and of the skins and their 
outgrowths, of the nervous systems, etc., would be equal- 
ly profitable. 

The book does not convey all the knowledge the pupil 
should acquire on the subject, neither is it intended to 
take the place of the teacher. It is designed, rather, to 
aid the capable teacher and guide the diligent and pains- 
taking worker. Many of the lessons need to be worked 
out in class with the use of material provided by the 
teacher. 

Xo special laboratory room is needed, though it would 
be convenient. A list of the supplies required will be 
found on a following page. The resourceful teacher 
will supplement the list by various illustrative materials 
as he finds opportunity. The absolutely indispensable 
supplies can be obtained at a very slight expense. 

The practical exercises woven in with the descriptive 



4 PREFACE 

text have been worked out by the author in many years 
of ninth grade teaching, and have proved thoroughly 
practicable. The pupil should keep a note book, and 
write in it the answers to the questions which occur in 
each lesson as well" as the supplementary work which 
may be given by the teacher. Most of the questions 
asked can be answered easily if the directions in the text 
are followed. The few difficult questions are asked be- 
cause they are questions that ought to arise at the places 
they are inserted. Why not learn in our school days 
that there are baffling problems for whose solution we 
shall have to wait a long time ? 

A resume of the first chapter is given at its close, as 
a sample. The pupil should write in his note book such 
a resume of each chapter. 

A few of the illustrations are original ; the others have 
been gleaned from various sources, most of them re- 
drawn and simplified. The author was assisted in pre- 
paring the illustrations by one of his former pupils, 
Reuben Schick, and by Mary Elida Porter. 

The author is also under obligation to the teachers of 
the Chicago high schools who have read portions of 
the manuscript and made valuable suggestions, — especial- 
ly to James H. Smith and Mary Bockes Pardee. Charles 
Louis Mix, M. D., and Winfield S. Hall, M. D., pro- 
fessors in the Northwestern University Medical School, 
and Dr. and Mrs. William Healy, also, have made help- 
ful criticisms. Special acknowledgment is also made to 
Dr. Anna E. Blount, who has collaborated with the au- 
thor through the entire work, has pruned out inaccu- 
racies, supplemented deficiencies, and written a number 
of pages. 

THE AUTHOR. 

Chicago, August, 1914. 



SUPPLIES 

The materials needed for the work outlined in the 
following chapters are here listed in sufficient quanti- 
ties for a class of twenty-four pupils. For larger classes 
it would be well to increase the quantity of each item. 
Several divisions doing the same work in one day could 
use much of the same material and so keep down the 
proportional expense. The material exhausted in using 
is estimated between three and four dollars for the 
class. Exclusive of the skeleton, the permanent equip- 
ment should not cost more than ten dollars. Nearly all 
the apparatus could be borrowed as needed from other 
science laboratories. Some of the observational work 
is to be done at home. The household articles used are 
not included in this list : 

Chapter 2. Two dozen glass tumblers $ .72 

Two dozen small dishes 72 

Chapter 3. An articulated skeleton can be had for from 
$30 to $40. The work can be done and the material passed 
around the class more conveniently if separate bones are 
used. A set would cost $15 or $20 and up, but incom- 
plete sets could be got for less. If human bones are 
not accessible, the bones of a cat, a dog, a pig, etc., will 
serve. 

Fresh bones and joints, from the market Jo 

Hydrochloric acid 05 

Chapter 4. A pound of fibrous meat cm into one 

inch pieces ■ ; 

5 



6 SUPPLIES 

Chapter 5. Half a dozen calf heads 50 

Half a dozen sheep necks 50 

Half dozen prepared stained sections of spinal cord, 

to be made in the Biological Laboratory. 

Chapter 6. A dozen sheep plucks 60 

A dozen or more seekers. These may be made by the 
pupils from strips of bamboo % inch wide, tipped with 
sealing wax, or charred at the end. 

Chapter 7. One dozen sheep lungs 25 

One dozen ]/ 2 inch test tubes, each with a ho 1 e in 
the bottom 25 

Chapter 8. Reagents for food tests — nitric acid, 
ammonia, iodine in potassium iodide solution, 
Haynes' solution, sulfuric acid 75 

One dozen test tubes ]/ 2 inch 25 

Bunsen burners or alcohol lamps. 
Food samples — brought by the pupils. 

Chapter 10. Two dozen small mirrors 40 

Extracted teeth — as many as an obliging dentist will 
give. 

Chapter ii. Two dozen hand magnifiers 5.00 

Pieces of torn leather. 

One dozen ink pads 1.50 

One ounce of ether, chloroform or alcohol 10 

Chapter 13. A. Mirrors listed in Chapter 10.... 
E. One dozen pairs of compasses 1.80 



CONTEXTS 

I. The Purpose of the Course 9 

II. Micro - Organisms 24 

III. Bones and Joints 32 

IV. Muscles 49 

V. The Nerve System 6$ 

VI. Circulation . 81 

VII. Respiration 108 

VIII. Foods 129 

IX. Stimulants and Narcotics 140 

X. Digestion . 159 

XL The Skin 187 

XII. The Kidneys and the Ductless Glands. 197 

XIII. The Special Senses 202 

XIV. Infectious Diseases 223 

XV. Disease, Drugs, and Doctors 238 

XVI. Sanitation 248 




DAVID di MICHELANGIOLO 
Accedemia di Belle Arti 



ARTEMIS of VERSAILLES 
Louvre, Paris 



PHYSIOLOGY AND HYGIENE 

CHAPTER I 
THE PURPOSE OF THE COURSE 

The body is the means by which we accomplish 
all we do, intellectual as well as physical. Consider 
how perfectly the two figures on the preceding 
page are adapted to express, — the one, strength, 
endurance, dignity; the other, grace, freedom, 
aspiration. AYe should all be pleased to have 
bodies as well adapted as these for the work and 
the play of life. Such bodies do not often come by 
chance. Nature supplies the possibility; we must 
work out the actuality. In the ardor of prepara- 
tion for an athletic contest, a boy will train per- 
sistently and conscientiously to bring his body to 
its best condition. Life is full of conflicts that try 
the mettle of any boy or girl. There is always the 
demand for a strong body to fight the battles. 
This book aims to help you to develop your bodies 
that they may be capable of expressing the 
courage and tenacity, tin- dignity and grace <>f 
your life. 

If you were entering upon a long journey, last- 
ing for many year-, and were obliged t<» make that 



IO PHYSIOLOGY AND HYGIENE 

journey in one machine, let us say an automobile, 
you would need to consider carefully that machine. 
You would need to study its construction, to know 
every part in its relation to every other part, to 
understand the origin of the power and how it is 
applied. You should be able to detect any flaws 
in the machine or in its working and, if necessary, 
to correct the troubles. 

Life is such a journey. You are given one 
mechanism, your body, with which to make this 
journey. You must, therefore, study it well, drive 
it carefully, and learn to stop and "overhaul the 
machine" when it seems out of order. Sometimes 
for good ends you may speed it up; at other times 
you must go slowly and put on all power to climb a 
steep hill, but you must never put the priceless 
thing to a needless risk. You should know the 
materials of this body-engine, the structure and 
use of every part, and how the parts all work 
together for one common purpose. You should 
know the source of your pow T er, and how that 
power is applied, set free to drive the engine. You 
should know the accidents that are most likely to 
occur, that you may guard against them; the im- 
perfections of the body-engine, that you may 
relieve the weak places from strain. You should 
watch for wear and attend to repairs in time, for 
though this is a self-repairing machine it must be 
given opportunity for repair. When any part is 



THE PURPOSE OF THE COURSE u 

worn past its own power of repair it cannot be 
replaced, its function is lost, and to this extent the 
work of the whole machine is impaired. 

Anatomy. The study of the construction of the 
human machine is called anatomy. By its deriva- 
tion the word means "to cut up," since the body 
must be dissected to get at its interior details. 
We shall learn these details through the study of 
parts of some lower animals and through pictures. 

Physiology. Each part of the body has a use, 
a function. The study of the functions of the parts 
and of the way all work together for the common 
good is called physiology. 

Hygiene. We study the body to the practical 
end that we may keep it well; in other w r ords, 
that we may run our machine to the best advan- 
tage. We are in good health when every part of 
the body is doing its w T ork well. It is of vital 
importance that we learn what wholesome things 
to do, and what harmful things to avoid, in order 
to maintain this condition. But there .is another 
way in which the body is unlike a machine; it is 
endowed with the power of growth and develop- 
ment. Year by year, from babyhood to manhood 
or womanhood, you should increase the power of 
the machine. You must, therefore, consider how 
best to develop your body. The stud}- of the laws 
of health, the development and care of the body, is 
called hygiene. 




12 PHYSIOLOGY AND HYGIENE 

Life unit — the cell. If we put under the micro- 
scope a little of the sediment from the bottom, or 
of the scum from the surface of some pond, we 
may find in it minute plants or animals whose 
essential structure is represented in this diagram. 
(Fig. i.) At the outside is a thin 
membrane called the cell-wall. 
Within is a fluid called proto- 
plasm, most of which is thin and 
watery. A denser part of the pro- 
toplasm, the nucleus, apparently 
Fig. i. Diagram more active and much more com- 
w^aK^roS Pleated in structure, appears as a 

plasm, n— nucleus, round or oval spot. The cell is the 
n — nucleolus. 

simplest form of life. Protoplasm 

is alive, and it is the only living substance known 
Tissue. The simplest forms of plants and ani- 
mals are composed of single cells or of a few cells 
joined together. The larger and higher forms are 
composed of many millions of cells of different 
sizes and shapes and having different functions. 
Millions of cells of one kind are grouped together 
to form the liver, cells of another kind form the 
brain, of still another kind form muscle, and so on. 
Cells may be joined together tightly, forming a 
compact mass, or they may be separated by inter- 
cellular substances which serve a useful purpose. 
For example, among the bone cells there is a large 
amount of intercellular stony material. A tendon is com- 



THE PURPOSE OF THE COURSE 



13 



posed almost entire- 
ly of intercellular 
threads. Such 
threads or fibers arc 
found in nearly all 
parts of the body, 
forming a frame- 
work for the softer 
parts. (Fig. 2.) A 
tissue is a group of 
cells of a certain 
kind or of cells and 
intercellular .sub- 
stances set apart to 
do a certain work. 
For example, there 
is liver tissue, com- 
posed of liver cells 
shaped and arranged 
in a certain way and 
having a special 
function; muscle tis- 
sue, recognized by 
cells of a distinctive 
form and function; 
brain tissue, marked 
by peculiar nerve 
cells; and so on for 
all the parts. 




Fig. 2. Fibrous intercellular ma- 
terial. The white fibers (a) appear 
as simple threads; among them are 
seen the cells which produce them. 
The yellow elastic fibers (b) arc 
much larger. How else do they differ 
from the white? The cells which 
produce them are not shown. The 
elastic fibers are found in a few 
stretching ligaments and in the walls 
of the arteries. The white fibers arc 
in most ligaments, in the tendons, 
and. in fact, in nearly every tissue. 



14 



PHYSIOLOGY AND HYGIENE 



Lymph. Besides the various kinds of tissue, the 
body contains fluids. In the minute spaces be- 
tween the cells and between fibers and in the large 

spaces between in- 
ternal parts of the 
body lies a watery 
fluid called lymph. 
This fluid holds in 
solution any of the 
body substances it 
can dissolve. 

The body is, then, 
a thoroughly porous 
mass of cells and in- 
tercellular sub- 
stances, the spaces 
are filled with a 
watery fluid, and all 
is covered with a 




Fig. 3. Various forms of cells, 
much magnified. A, a nerve cell from 
the spinal cord, magnified 100 times. 
B, a muscle cell from the wall of an practically water- 
artery, magnified 350 times. C, cells 



from the surface of a serous mem- 
brane. D, section from the mucous 
membrane of the intestine. E, sec- 



tight skin. 

Cell form. The 

tion across a tube of the salivary form Q f each spec i a l 
gland. l 

kind of cell is adapt- 
ed to its work. Study Part A of Fig. 3, represent- 
ing a nerve cell from the spinal cord. Tl>is nerve cell 
has to receive and send out nerve currents. The out- 
going current goes over the single large fiber, the incom- 
ing current comes through the root-like projections. 



THE PURPOSE OF THE COURSE 15 

1. Does the cell seem to be able to receive currents 
from only one, or from several sources? 

2. About what is the diameter of the main part of the 
cell, if the figure is in length one hundred times the 
natural size? 

3. What is the length of the muscle cell, if drawing 3 
multiplies it three hundred fifty times? 

4. How is the shape of the cell adapted to its work of 
contracting? 

5. The cells in C are thin ; describe their shape. 

6. Would any other form of cell cover a surface so 
compactly ? 

7. In part D the cells are viewed from the side. Their 
top surface forms the surface-lining of the intestine. 
They are fastened to the membrane at the base. Would 
you infer from their length that they have any important 
function other than to make a tight lining? 

9. How are the cells of the salivary gland arranged 
with reference to the small tube which carries away the 
saliva they produce? 

Protoplasm. The substance known as proto- 
plasm resembles the raw white of egg. It is 
watery and colorless. Chemically it is composed 
of four chief elements — carbon, hydrogen, oxygen, 
and nitrogen, and of a number of other elements in 
very small quantities, among which are sulphur, 
phosphorus, and potassium. Protoplasm is the liv- 
ing substance. Since it is to be the chief object 
of our study, we need to understand what is meant 
by a living substance, and that is much the same 
as knowing what protoplasm can do. 



i6 



PHYSIOLOGY AND HYGIENE 



1. Protoplasm can assimilate food; that is, it 
can take into itself certain food substances and 
make them over into material like itself. This 
production of new protoplasm is involved in all 
growth and repair. There is no other known way 
in which protoplasm can be produced. 

2. The cell, which is the unit of protoplasm, can 
divide so that the number of cells increases. The 

nucleus, by a com- 
plicated process, di- 
vides into two nu- 
clei, a line of sep- 
aration forms be- 
tween them, and 
there are two cells 
instead of one. 
(Fig. 4.) Increase 
in the number or 
size of cells is 

Fig. 4. Diagram to show the growth in animals 
changes a nucleus undergoes in cell 1 1 , 

division. The nucleus is shown oc- ancl plants. 




cupying more of the cell than it 
usually does. 



3. Protoplasm 
can move. In plant 
cells it can be seen circulating in tiny streams 
about the cell; in muscle cells it contracts and 
expands, the long cells becoming alternately 
shorter and thicker, then longer and thinner. 

4. Protoplasm is irritable; that is, it acts in re- 
sponse to a stimulus. If you touch a one-cell 



THE PURPOSF. 01 : THE COURSE 



17 



animal, he draws away; if a food particle conies in 
contact with him, he advances and surrounds it. 
While all the protoplasm of the higher animals 
responds to some extent to stimuli, the nervous 
system is most highly irritable. The common way 
of distinguishing live protoplasm from dead is 
to apply a stimulus and see if the protoplasm 
responds. 

5. Protoplasm breaks down, or undergoes chem- 
ical change, when it acts. In the process of assim- 
ilation, protoplasm is built up into a very complex 
but unstable substance. You remember it con- 
tains carbon, hydrogen, oxygen, etc. When the 
protoplasm acts (secretes, contracts) some of the 
oxygen combines with the hydrogen, forming 
water (H 2 0), and other oxygen combines with 
the carbon, forming carbon dioxide (C0 2 ). Thus 
more simple and stable substances are formed by 
the tearing down of a complex, unstable substance. 
This is a process essentially like the burning that 
takes place in a furnace, only slower. It is called 
oxidation, because the hydrogen and carbon com- 
bine with oxygen. The fuel in the furnace is com- 
posed mostly of carbon (C). The draft admits the 
air containing oxygen (O) and in the heat of the 
fire the fuel is broken up, and each atom of carbon 
combines with two atoms of oxygen, forming the 
carbon dioxide (C0 2 ). These chemical 
changes in the protoplasm, as in the furnace, de- 



l8 PHYSIOLOGY AND HYGIENE 

velop electricity, heat, motion, and other mani- 
festations of energy. In the complex protoplasm 
there is much stored-up energy which is freed upon 
its breaking down. In fact, the disintegration of 
the protoplasm is largely for the purpose of trans- 
forming its energy into the various forms of work 
— secretion, heat, and motion. The resemblance 
to the furnace is very close. The food taken into 
the protoplasm corresponds to the fuel of the fur- 
nace. The burning of the fuel is for the purpose 
of transforming its stored-up energy into the mo- 
tion of the engine. So the oxidation of the food 
in the protoplasm transforms its energy into the 
activities of the cell. 

Energy. We have spoken of protoplasm as an 
energy producer. Energy is power to do work, to 
produce changes in the condition of a body, such 
as moving, producing an electrical or chemical 
change, melting ice, evaporating water, etc. There 
is a law of nature called "conservation of energy/' 
This means that energy cannot be destroyed or 
produced. It is transformed from one kind of 
manifestation to another. Thus heat energy is 
transformed into motion in the steam engine, and 
chemical energy is transformed into electric energy 
in the battery — with no loss in quantity during the 
transformation. So true is this that, knowing the 
amount of energy liberated by burning a pound of 
coal, we can figure the amount of coal and oxygen 



THE rURFOSF. OF THE COURSE 



19 



necessary to produce a given amount of electricity, 
heat, or mechanical work. The flood of rays 
streaming' from the sun to the earth supply us 
with nearly all the energy we have. The rays, 
that seem so simple, manifest themselves in various 
ways. To the eye they are light; to the skin they 
are warmth; on the photographic plate they make 
pictures; within the green leaf laboratory, the pro- 
toplasm of the plant, they build up sugar or starch, 
the fundamental substances on which all plant and 
animal life rests. From the air the carbon dioxide 
(COo) enters the leaf; from the ground comes the 
water (H 2 0). The energy of the sun's rays com- 
bines these two substances into sugar and sets 
free some oxygen. 

12 molecules of) f 11 molecules^_ f 1 molecule 1 M f 12 molecules 
carbon dioxide J \of water J \of sugar J ' \of oxygen 
12 CO, 11 H,0 = C«H«On + 12 O: 

The energy of the ray is stored up in the sugar, 
or more accurately stated, in the affinity of the 
>ugar for oxygen. If the sugar should combine 
with oxygen, oxidize, or burn, C0 2 and H 2 would 
be produced, and the stored-up energy would 
appear as heat. 

1 molecule^ _f 12 molecule>)_( 12 molecule- 1 1 molecule- 

of sugar J ' [of oxygen J \nf carbon dioxide J [of water 

CuH^O: 12 Ol = 12 CO: II H 2 

For the upbuilding of the highly complex pr<>t<>- 



20 PHYSIOLOGY AND HYGIENE 

plasm a great deal of energy is used, all of which 
appears again as heat or motion or in some other 
form when the protoplasm breaks down. We say 
that energy is stored up in sugar, in fat, in coal, 
in protoplasm because all the energy that went into 
their upbuilding can be utilized again as heat or 
light or motion when the food or fuel is oxidized. 
We must not lose sight of the fact that the body 
is an engine, a living engine to be sure, but one 
that uses the ordinary forms of energy, transform- 
ing them for its purposes to produce muscular 
activity and heat and to elaborate chemical 
substances. 

The needs of protoplasm. Protoplasm can sus- 
tain its life only under certain conditions. Con- 
sider the protoplasm of a cell of the brain or of a 
muscle. The muscle contracts or the brain cell 
sends out a nerve current; some of the protoplasm 
is torn down to simpler compounds, waste prod- 
ucts. Let the action be repeated. The protoplasm 
is soon worn out by the oxidation process. That it 
may remain alive, capable of carrying on its char- 
acteristic life activities, the loss must be restored. 
The protoplasm builds itself up again from the 
food and oxygen brought to it. Therefore the 
needs of protoplasm are (first) food and (second) 
oxygen. 

I. To maintain its life protoplasm must be sup- 
plied with food. 



THE PURPOSE OF THE COURSE 21 

2. For activity protoplasm must have oxygen. 

3. As a result of the tearing down of the proto- 
plasm there is present in it carbon dioxide and 
other products of oxidation. These waste products 
are injurious to the protoplasm and must be re- 
moved. It is the blood and lymph, circulating- 
through the body, that bring the food and oxygen 
to the cells and remove the products of oxidation. 

4. If the hand is held in boiling water, or if the 
skin is severely frozen, its life is destroyed. To 
preserve life the temperature of protoplasm must 
be kept within certain limits. What the limits are 
differs with different protoplasm. Some plants and 
small animals remain for weeks at a temperature 
considerably below freezing, and some can endure 
even boiling for a short time. The cells of the 
human skin can endure the temperature of hot 
water (perhaps 115 degrees) and for a short time 
a freezing temperature (32 degrees), but if the 
interior of the body reaches a temperature as high 
as no degrees or as low as 95 degrees death is 
likely to occur. The mouth temperature is on the 
average 98.6 degrees, and in health does not depart 
more than a degree from this. 

5. Protoplasm needs to be kept moist. Active 
protoplasm requires a good deal of water and i^ 
easily killed by drying. Yet seeds in maturing 1, 
most of their water and may remain dry in a rest- 
ing condition for years. They can resume their 



22 PHYSIOLOGY AND HYGIENE 

activity in sprouting only after they have absorbed 
a large quantity of water. 

These five conditions must be maintained con- 
tinually for the protoplasm in all parts of the body. 
Except for propagation of its own kind, the entire 
physiological activity of every living animal, the 
structure and work of every organ of the body 
has for its end the maintenance of these five condi- 
tions — together with one other, protection against 
injury. Our study must make clear how all parts 
of the body work together to accomplish these 
ends. Each lesson should add something to the 
solution of this problem, and you have not finished 
the study of any organ or process until you under- 
stand the part it plays in this co-operative work. 

SUMMARY 

A sound and able body is needed for such life as we 
all desire. Life is a journey; the body is the engine that 
carries us through. We must learn to manage it well. 

Anatomy treats of the structure of the body, physiology 
of its functions, and hygiene of its care — the practical 
end of our study. 

The unit of structure of the body is the cell, com- 
posed of protoplasm, w r ith usually a nucleus and often 
a wall. 

Tissues are groups of many cells of the same kind, 
having a special function, together with characteristic 
intercellular substances. 

The minute spaces in tissues and the larger spaces 
between organs are filled with a circulating fluid called 



THE PURPOSE OF THE COURSE 



23 



lymph. The skin is a water-tight covering to keep this 
fluid from escaping from the body. 

Cells have many forms, each adapted to the special 
work it has to do. 

Protoplasm is composed of four chief elements, car- 
bon, hydrogen, oxygen and nitrogen, with several minor 
elements. 

Protoplasm can assimilate, multiply, move, respond to 
stimulus, and liberate energy in breaking down. 

The energy manifested on the earth comes from the 
sun. Energy cannot be produced or destroyed, but may 
pass from one form of manifestation to another. The 
fundamental life activities are the transformations of 
energy- involved in the upbuilding and down-breaking of 
protoplasm. 

Protoplasm needs food, oxygen, removal of waste, tem- 
perature kept within certain limits, moisture and protec- 
tion. All parts of the body co-operate to provide these 
necessities. 



CHAPTER II 
MICRO-ORGANISMS 

At the outset of our work we must consider 
some groups of small plants and animals that are 
very influential for good or for evil in the life of 
man. Since they affect nearly all parts of the body, 
it is important that we understand them at the 
beginning of our study. They are called bacteria 
germs, micro-organisms, or microbes, and are com- 
monly single cells, so exceedingly small that hun- 
dreds of them could be held on the point of a pin. 
Single germs can be seen only with a microscope of 
high power. 

Bacteria. The more common vegetable germs 
are bacteria and they are so small that no interior 
structure can be seen. They appear to be specks 
of protoplasm encased in a wall of such material 
as that which forms wood and paper. Under 
favorable conditions bacteria increase in number 
very rapidly by simply dividing. In a warm, moist 
food material a single germ could, in the course of 
twenty-four hours, multiply to over 16,000,000. 
Some kinds of bacteria are able to move by means 
of tiny threads of protoplasm projecting from 

2 4 



MICRO-ORGANISMS 



25 



their surface, but most varieties move only as they 
are carried by wind, water, animals, and like means. 

1. What appearance have bacteria when moderately 
magnified ? 

2. What shapes do they show when very highly mag- 
nified ? 

3. What are their diameters in Fig. 5 ? 

4. Compute the size of the germs themselves. 



'<*> 



'•t 



Q££3cr2»e*Li? 



<sa 



*** 



i#t 




B 




FlG. 5. Micro-organisms. A. bacteria magnified 500 or 600 
times; B, bacteria magnified about 2000 times; C, yeast; D, a 
ring-worm parasite ; E, plasmodia of malaria. 

Other microbes. There are a few kinds of veg- 
etable germs other than bacteria which produce 
infectious diseases; for example, a variety of yeast 
and some mould-like forms. But the diseases they 
cause are not common. Several very common dis- 
eases, however, are produced by microscopic one- 
cell animals called plasmodia. These germs are 
speck- of bare protoplasm, usually larger than 



26 PHYSIOLOGY AND HYGIENE 

bacteria. They have the power of drawing in or 
pushing out any part of their minute bodies and so 
changing their shape. 

Microbe life conditions. All of these microbes 
require for their "life favorable conditions of food, 
oxygen, moisture, and temperature mentioned in 
the preceding chapter. Some are able to resist a 
temperature almost equal to boiling, while freezing 
does not kill them. They sometimes go into a sort 
of resting stage and form about themselves a tight 
shell. This drying, however, does not destroy 
them. They are later blown about, and some finally 
drop into a moist substance which serves as food. 
Here they soften and resume growth. They differ 
a great deal in the substances they require for food. 
Most of them would flourish in the food that nour- 
ishes us, while many live in surroundings that 
would seem to us most unwholesome, as in the 
bodies of decaying plants and animals. 

How studied. Germs are so small that it is 
impossible to distinguish the different kinds merely 
by their appearance under the microscope; all their 
life peculiarities must be studied. They are put in 
small glass dishes in the laboratory, supplied with 
food, and kept at a certain temperature. Gelatine 
containing beef broth is a food commonly used. 
As the germs grow they produce spots in the jelly; 
some liquefy the jelly as they grow, others do not ; 
some grow rapidly, some slowly; some have strik- 



MICRO-ORGANISMS 



27 



ing color, as red or yellow. By these various 
peculiarities, as well as by their appearance under 
the microscope, they are recognized. 

For the cultivation of a few kinds of germs found 
in the water or air, a boiled potato is easier to pre- 
pare than the beef broth gelatine. After washing 
the potato clean, boil it for about a half hour. 
When it is cool, cut it into a few thick slices with 
a sterile knife (one that has been boiled, held in 
a flame, or rinsed in alcohol or some other anti- 
septic solution). On one slice of potato put a few 
drops of water from the tap; on another a few 
drops of milk; touch one to the floor; touch an- 
other to your hand; let another stand in the air 
for fifteen minutes. As soon as each piece is 
exposed, place it in a saucer on a piece of blotting 
paper wet with boiled water and cover it with a 
clean tumbler. Stand it in a warm place and look 
at it every day for a week or two, to see the 
growth of the colonies of mould and bacteria. 
Most disease germs will not grow on potato. Some 
resist all attempts at cultivation outside the human 
body. 

Products. As the germs grow they produce cer- 
tain substances. For instance, yeast in a solution 
containing sugar produces carbon dioxide and alco- 
hol; bacteria in meat produce the poisons of 
tainted meat; others in milk produce the acid of 

ir milk. Most, if not all, disease germs produce 



28 PHYSIOLOGY AND HYGIENE 

a poison — each kind of germ its own special poison 
— called toxin. 

Beneficial microbes. There are hundreds of 
kinds of microbes and, though many produce poi- 
sons or cause diseases by growing in the body, a 
much larger number are not only harmless but 
very beneficial. In fact, we could not live without 
them. Soil is made fit for plants by the microbes 
in it. The ground would soon become covered 
with leaves, sticks, tree trunks, and the bodies of 
dead animals if they did not decay, through the 
work of bacteria-and other minute organisms. The 
ripening of cream for butter, the maturing of 
cheese, the rising of bread, and the fermenting of 
liquors are accomplished by various bacteria. 

Guarding against microbes. We have learned 
several ways of protecting ourselves against harm- 
ful germs. Meats, vegetables, and fruits are pre- 
served against decay by cold storage, for the bac- 
teria that cause decay increase very slowly, if at 
all, at the freezing temperature. A very high tem- 
perature kills germs, so we boil drinking water 
which we suspect of containing disease germs. If 
meats, vegetables, and fruits are well boiled, and 
sealed in air-tight cans while still boiling hot, they 
will keep an indefinite time. Canning is a scientific 
process. One woman has "better luck" than her 
neighbor because she has her jars clean (free from 
germs), puts the fruit in boiling hot, and immedi- 



MICRO-ORGANISMS 



2 9 



ately screws the tops on tight. It is all a matter 
of leaving no live germs in the jars and giving 
none a chance to get in. 

Substances that contain no live germs are said 
to be sterile or aseptic. Make the following experi- 
ment in sterilization: Into several test tubes put 
some food substance, milk, broth, fruit juice, or nu- 
trient gelatine, to the depth of about two inches. 
Plug each tube with a snug-fitting but not too tight 
stopper of absorbent cotton. Stand the tubes in a 
dish of water and boil for at least a half hour. 
When the tubes are cool, remove the cotton plugs 
from half of them and let them stand open in the 
room. Keep the remaining tubes closed. Observe 
the tubes from day to day and explain the changes 
you see. Do germs go through a plug of dry 
cotton ? 

Antiseptics. Substances that kill or check the 
growth of germs are called antiseptics. The most 
efficient antiseptics are strong poisons, which must 
be handled with great care. Corrosive sublimate 
(mercury bichloride) and carbolic acid are used in 
dilute solution in washing the surgeon's hands and 
instruments and in cleansing wounds. Formalin 
and the fumes of burning sulphur are employed in 
disinfecting rooms and clothing used by a patient 
suffering from an infectious disease. Boracic acid 
i- used in washing a tender surface such as the eye 
or a wound. Borax preparation- are used also in 



3 o PHYSIOLOGY AND HYGIENE 

preserving meat, and it is claimed that they do not 
injure the wholesomeness of the food. Salt, used 
in large quantities, is an antiseptic, and is there- 
fore used in preserving meats, fish, and pickles. 
Smoke also preserves meat because it contains the 
antiseptic creosote and because it leaves the sur- 
face of the meat dry and firm and thus impervious 
to germs. 

Prepare some slices of potato for germ cul- 
ture as directed on page 2j. After they have been 
exposed to the germs, spray them thoroughly with 
an antiseptic — formalin or alcohol — and cover them 
with clean tumblers. In test tubes containing milk, 
broth, or fruit juice put a few drops of carbolic 
acid or formalin or a few grains of mercury- bi- 
chloride and shake thoroughly. Stand the tubes in 
a warm room. Do bacteria and moulds grow in 
these poisoned foods, as they did in the foods not 
treated with antiseptics? 

Microbes and disease. It is in relation to dis- 
eases that microbes are of most interest to us here. 
That they are the direct cause of many infectious 
diseases has been proved beyond any question. 
Certain germs have been found in the bodies of 
the sick, studied under the microscope, cultivated 
in the laboratory, introduced into the bodies of 
healthy animals, and have produced the same dis- 
ease as that which afflicted the person from whom 
they were taken. We get the infectious disease by 



MICRO-ORGAN ISMS 



31 



taking into our bodies the disease microbes, and 

we get it in no other way. Tt has not been proved 
that all infectious diseases are caused by minute 
plant or animal parasites- — germs, but it is quite 
probahle. The difficult}- of proof lies in the fact 
that some germs can hardly be separated from 
others, in whose company they occur, and cultivated in 
the laboratory. It is supposed that each infectious 
disease either has its own special germ, which pro- 
duces only that one disease (as, for instance, diph- 
theria), or it may be caused by any one of several 
germs (as in meningitis), or by several kinds of 
germs co-operating to produce it. Several kinds 
of bacteria are sometimes found together in boils 
and carbuncles. 

Whenever pus occurs it is caused by microbes, 
sometimes one kind, sometimes another, sometimes 
several kinds together. Pus is a fluid filled with 
germs and white blood corpuscles, usually creamy, 
sometimes bluish, or, if stained with blood, pink. 

In the pages that follow we shall have frequent 
occasion to refer to the relations of germs to vari- 
ous parts of the body. Two entire chapters (XIV 
and XVI ) are given to the discussion of diseases 
caused by germs and to the methods of treating 
and preventing them. 

Note. — The pupil should write a summary of this and of each 
following chapter, observing the form of the summary given at 
the end of Chapter I. 



CHAPTER III 
BONES AND JOINTS 

In this chapter you will learn why the human 
body needs bones, how their structure is adapted 
to their use, and how they maintain their own 
life; why the body needs joints, what their essen- 
tial parts are, the function of each part, and how 
the different kinds are suited to different uses. 

Uses of bones. There are some animals of mod- 
erate size that have no bones and no hard parts 
that serve the purpose of bones. They are slow 
of movement and are buoyed up only by the water 
in which they live. 

1. From a study of the figure of the human skeleton 
(page 33) name several bones whose function is the sup- 
port of soft organs. 

2. Name others which protect parts of the body. 

3. What bones are especially used in movement ? 

4. What is the most important characteristic of their 
shape ? 

5. What service can the arm, because of its bones, per- 
form better than an organ such as the elephant's trunk? 

The general skeleton. If a set of human bones 
cannot be had, the skeleton of a cat, a dog, or other 
mammal may be used in answering the following 

32 



BOXES AND JOINTS 



33 




i. Clavicle or 
collar fy 

2. Ril). 

3. Scapula or 

shoulder 

blade. 

4. Humerus. 

5. Pelvis or hip 

bones. 

6. Radius. 

7. Ulna. 

8. Carpal or 

wrist bones. 

9. Metacarpal or 

hand bones. 

10. Phalanges or 

finger bones. 

11. Femur or 

thigh. 

12. Patella or 

knee cap. 

13. Tibia. 

14. Fibula. 

15. Tarsal or 

ankle bones. 

16. Metatarsal or 

foot bones. 

17. Phalanges 

toe bones. 



Fig. 6. 



34 



PHYSIOLOGY AND HYGIENE 




C0CCf*_^ 



questions. See also the 
figure of the skeleton, 
Page 33. 

1. What is the main axis 
of the skeleton ? What is 
one section of this called? 

2. Of how many verte- 
brae is it composed? (See 

Fig. 7-) 

3. Which of the verte- 
brae have ribs attached to 
them? 

4. Why should the lower 
vertebrae be so much 
stronger than the upper ? 

5. What two bones make 
the joint that allows the 
free rotation of the head? 

6. How many ribs are 
there on each side? 

7. To what are the upper 
seven ribs attached on the 
front or ventral side? 

8. Explain the difference 
in the ventral attachment 



Fig. 7. The spinal column 
from the left side. The white 
space between two vertebrae is 
cartilage. At its dorsal border 
(right) is an opening into the 
spinal canal. The shaded round 
spot on the centrum and on the 
lateral process of each thoracic 
vertebra is the place where the 
rib joins. 



BONKS AND JOIN - jj 

of the eighth, ninth and tenth ribs; of th nth and 

twelfth. 

9. Observe the shoulder girdle and the pelvic girdle, 
with their dependent limbs. Which girdle is er? 

Why need it be? 

10. Write in one column the names 01 the bones of the 
arm and hand, and in a parallel column those of the b 

of the leg and foot, placing the names of like bones oppo- 
site each other, and underscoring those which have no 
corresponding bones. 

Study of a Long Boxe 

1. How do the extremities of a long bone differ in 
diameter from the shaft? 

2. In the longitudinal section, how do the extremit 
differ in structure from the shaft? 

3. Why could not the shaft just as well have the same 
spongy structure as the ends ? Why could not the ends 
just as well have the dense structure of the shaft? 

4. The rough protuberances and depressions are for 
the attachment of muscles and tendons : where are they 
most numerous ? 

5. Give as many reasons as you can why the end- r 
to be larger than the shaft? 

6. In a section of fresh bone, what occupies the middle 
of the shaft? 

7. Why is it better, from a mechanical standpoint, to 
have the shaft hollow instead of solid? 

8. Where do you find openings for blood vessels and 
nerves to enter the bone ? 

9. On the outer surface of a fresh bone, loos mall 
part of the periosteum (covering membrane) and de- 
scribe it. 



36 PHYSIOLOGY AND HYGIENE 

10. Make a sketch of a longitudinal section and name 
the parts. 

Study of a Short, Irregular Bone 

i. In the section of a short bone is the bone composed 
of spongy or of compact tissue. 

2. Where do you find openings for blood vessels and 
nerves ? 

3. Where are the places for muscle or tendon attach- 
ments ? 

4. Describe the surface of the bone where it moves on 
another bone. 

Study of the Shoulder Blade — Scapula 

i. Are your own shoulder blades firmly or loosely 
attached to your ribs? 

2. What uses has the large crest on the dorsal side 
of the bone? 

3. Describe the surface where the arm bone (humerus) 
joins the scapula. 

Study of the Hip or Pelvic Bones 

1. Why is the pelvis shaped like a bowl? 

2. Is it closed or open at the bottom ? 

3. Why is the dorsal part so much stronger than the 
ventral part? 

4. The bone upon which the vertebral column rests is 
called the sacrum. It is formed by the union of how 
many vertebra-like bones? 

5. Of what use is the deep socket on each side of the 
pelvis ? 

6. Where do you see rough surfaces or projections for 
the attachment of muscles? 



BONES AXD JOINTS 37 

Study of a Rib 

1. Describe the general shape of a rib. 

2. Can you bend your ribs? What is the advantage 
of this condition? 

3. How does the ventral part differ in form from the 
dorsal part? 

4. How many smooth spots, for joining other bones, 
do you find on a rib ? 

Study of a Vertebra 

1. Notice the two general parts — the body or centrum 
and the dorsal arch. A projection from a bone is called 
a process. 

2. From which part of the vertebra do the dorsal and 
the lateral processes project? Large muscles lie length- 
wise of the body along these processes. 

3. Of what use are the anterior and posterior processes 
from the dorsal arch ? 

4. What part of the vertebra lies ventral to the large 
canal holding the spinal cord ? What part lies dorsal ? 

5. Where is there a place for the spinal nerves to leave 
the canal? 

6. Make a sketch of a vertebra, end view, and name the 
parts. 

Study of the Skull 

(a) The Cranium (brain case). 

1. Sketch about one-half inch of a suture, the joining 
of two bones. 

2. Describe the three layers seen in a section of the 
roof bones. 

3. How do the floor bones differ from the roof bones 
in thickness? 

4. Where i^ the opening for the spinal cord? 



38 PHYSIOLOGY AND HYGIENE 

5. Where does the first vertebra join the skull? 

6. Where are the small openings through which blood 
vessels and nerves pass? 

(b) The Facial Bones. 

7. Is the upper jaw firmly or movably fastened to the 
skull? 

8. Does the lower jaw hinge to the skull before or 
behind the ear? 

9. Where are the rough places and projections to 
which are attached the muscles that close the jaw? 

10. Where are the openings through which nerves 
from the lower part of the face enter the jaw bone? 
Where do these nerves and those from the lower teeth 
come out of the bone? 

11. By what means are the teeth held firmly in place? 

12. What kind of partition separates the two nasal 
cavities ? 

13. By what sort of bone is the inner surface of the 
nose cavity enlarged? In life this bone is covered by a 
membrane. 

Composition of bone. Put a piece of dry bone 
into a bottle of dilute hydrochloric acid. What 
do you see rising through the water from the sur- 
face of the bone? This is the gas, carbon dioxide. 
It is produced by the action of acid on the lime- 
stone (calcium carbonate) in the bone. About 
two-thirds of the bone is stony matter, calcium car- 
bonate and calcium phosphate. Describe a bone 
that has been soaking in acid several days, until 
all the stony substance has been dissolved. The 
material that remains is animal substance. It may 



BOXES AND JOINTS 39 

be taken out of the bone by burning, but the burn- 
ing changes the stony material also. The burnt 
bone is more fragile than it would be if the animal 
substance were removed without affecting the min- 
eral. The stony and the animal substance of the 
bone are so intimately mingled that even the small- 
est particles contain both elements, therefore the 
shape is unchanged when all of either substance 
is removed. 

1. The bone owes its stiffness to which substance? 

2. To which substance does it owe its toughness? 

3. What difference in composition makes a child's 
bones more flexible than those of an adult? 

Minute structure. You must understand that 
bone tissue is alive, and that every part of it mUot 
be supplied by a fluid from the blood which brings 
food and oxygen and carries away waste. Figure 8 
shows a microscopic section of dense bone, such as 
knife handles are made of. Around what as a cen- 
ter do the concentric layers of bone lie? What 
is the diameter of these canals which contain the 
blood vessels? From them the fluid must ooze 
through the canaliculi to the protoplasm, which 
lies in the small irregular cavities. Between these 
cavities which contain the bone cells, penetrated by 
the canaliculi. lie intermingled the gristly and the 
stony substance- of the bone. 

Periosteum. Covering the bone everywhere ex- 
cept at the joints is a tough membrane called peri- 



40 



PHYSIOLOGY AND HYGIENE 



osteum. If the bone is broken or a piece taken out, 
the cells of the periosteum produce material to 
repair the injury. From these new cells grow out 
and soon change into bone tissue. 




TWO 
LACUNAE 

X500 



Fig. 8. A, a longitudinal section of bone. B, a transverse sec- 
tion, of bone. Both are magnified about 75 times. H, Haversian 
canals. The black specks are lacunae. Each of the two shown 
more highly magnified is filled with a cell. The canaliculi connect 
the cells. 

Germ disease in bone. Bones as well as other 
parts of the body suffer from germ diseases. What 
is there in bones which can serve as food for 
microbes? If a bone or a considerable part of a 
bone is destroyed by germs, deformity is likely to 
result. Tuberculosis often causes hunchback, and 
occasionally affects bones in other parts of the 
body. Some other contagious diseases also affect 
bones. If a disease is checked when the bone is 
only partially destroyed the periosteum and the 
bone cells set about repairing the damage, but 



BOXES AND JOINTS 



41 



they often produce a superabundance of bone ma- 
terial and make a large lump on the bone and this 
appears as a deformity. 

Fracture. When the bone of an adult is frac- 
tured, the brittle, stony substance, and also the 
tough animal substance, are broken in a rough sur- 





Fig. 9. A, "green -tick" fracture of the radius. B, a fracture 
of the tibia. The contraction of the leg muscles would have 

what effect on the length of the broken leg? 

face, and the cells of the bone and of the periosteum 
are torn. In the healing process perhaps the bone 
cells and surely the periosteum cells adjacent to 
the injury multiply and fill the break. Gradually 
strong bone material replaces these soft cells, fas- 



42 PHYSIOLOGY AND HYGIENE 

tens together the broken ends, and makes the bone 
as strong as ever — perhaps stronger than before, 
for the new growth often covers the break with a 
large callus. This lump does no injury on the 
shaft of a long bone, but at a joint it may seriously 
obstruct freedom of motion. 

It is especially important that the broken bone 
be kept quiet during the time of "knitting." If 
the broken ends are moved on one another before 
the filling material has hardened, the union is likely 
to be imperfect, the bone crooked, or the callus 
very large. Sometimes people use a broken limb 
as soon as the swelling and the pain have disap- 
peared, and then blame the physician if the break 
does not heal perfectly. 

Sometimes breaks in children's bones are called 
"green stick" fractures, because the bone does not 
snap off like a dry twig, but bends and cracks like 
a green shoot. The small amount of stony sub- 
stance breaks, while the tough animal material 
bends and often holds the bone together. This 
break is quickly healed, but the bone should be 
carefully guarded against strain until it has recov- 
ered its full strength. 

Rachitis, Rickets. One of the most common 
causes of deformity and under-development of 
bones is deficient nourishment of small children. 
Although the child may get a sufficient quantity 
of food, he may not get the lime salts necessary 



BOXES AXD JOINTS 43 

for stiffening* the bone. This lack of nutrition 
results in a disease called rickets, one of the symp- 
toms of which is weak and crooked bones. The 
leg bones become bowed under the weight of the 
body, though not all bow legs are due to rickets. 
The arms and skull and other bones are affected. 
The disease is easily cured if the child is given a 
proper diet before the bones become hardened in 
their distorted form. The teeth are composed of 
the same substances as are the bones, and often 
show by their easy crumbling the deficiency of the 
diet. 

Effect of alcohol on the bones. Some parents, 
not understanding the evil they are doing, allow 
their little children to partake of the alcoholic 
drinks they are themselves using. This often im- 
pairs the nutrition of the child and causes rickets. 
A moderate use of alcohol in adults has no notice- 
able effect on the bones, but in confirmed inebriates 
the bones suffer with the remainder of the body. 
A break heals only with great difficulty, and some- 
times the fracture of a bone precipitates an attack 
of delirium tremens. 

Joints. Where two bones come together they 
make a joint. In some cases the bones are (irmly 
fastened together, and in other cases they move 
one on the other. Find in the skeleton several 
instances of the first case. In the fixed joints the 
bones are clearly separate in childhood, but in old 



44 PHYSIOLOGY AND HYGIENE 

age they are so firmly grown together that they 
appear as one. Why should not the bones of the 
cranium be firmly grown together in childhood? 
Structure of a joint. In a dry specimen observe 
whether the bearing surface of the bone at a mov- 
able joint is smooth or rough. This surface in the 
live bone is covered with cartilage instead of with 
the periosteum which encases the remainder of 
the bone. 

i. Describe the cartilage in a fresh specimen — its color, 
thickness, etc. Is it firm or yielding? 

2. What is the color of the ligaments binding one bone 
to another? 

3. Are they firm or soft? 

4. Can they be stretched like rubber? 

5. Has the dry bone where the ligaments fasten a 
smooth, or a rough surface? 

6. The joint cavity is the inside of a closed sack called 
the synovium. The outside of the synovium grows so 
tightly to the cartilage and ligaments that it can scarcely 
be distinguished from them. As the joint moves all the 
rubbing surface is inside of the synovial sack. What sort 
of a surface is it? 

7. Describe the synovial fluid which lubricates the joint 
— its color, feel, etc. 

Movements and Forms of Joints 

1. Study the skeleton, Fig. 6, and determine in which 
bone is the socket, and in which the ball of the hip joint. 

2. Stand and move your own leg at the hip; in what 
direction can a ball and socket joint bend? 



BOXES AND JOINTS 45 

3. Find another joint that has the same free move- 
ment and seems to be a ball and soeket joint. 

4. In what direction can the knee joint move? 

5. Find another joint that has a hinge form. 

6. Move the jaw from side to side. This is a sliding 
or gliding joint. 

7. What would lead you to think that the wrist and 
ankle may also glide ? 

8. In a dry skeleton observe how the first vertebra is 
joined to the second. This is a pivot joint. It allows 
what movement of the head? 

9. Name four kinds of joints studied in this paragraph. 

Dislocations and sprains. When the movement 
of a bone at a joint is forced, the bone may slip out 
of place, so that the muscles can no longer bend 
the joint. This is called a dislocation. If the liga- 
ments are very slack dislocations occur easily, but 
the dislocated bone may slip back into place 
just as readily. Frequently dislocation tears some 
of the fibers of the ligaments, and healing requires 
several weeks. After the dislocated bone has been 
brought into place, the joint is bandaged to hold 
it secure. After a few clays the joint is bent back 
and forth carefully and exercised every day to 
prevent stiffness. 

If, however, the movement is so violent as to 
tear some fibers of the ligament, and yet not dis- 
place the bones, the accident is a sprain. A Sprain 
may also involve the bruising of the cartilage at 
the end of the bone. It is a very painful injury, 



46 PHYSIOLOGY AND HYGIENE 

slow to heal, and should be treated with great care. 
The swelling of a sprain is caused by the lymph 
and blood flowing into and often filling the joint 
cavity and surrounding tissue. Gentle rubbing 
helps to reduce it. Hot dressings are used to re- 
lieve the pain. If no infection occurs the sprain 
usually heals without stiffness. In case of infec- 
tion the injury should have the attention of a 
surgeon. 

The feet. The bones and joints of the feet suffer 
severely from unhygienic shoes. Shoes that are 
too large rub against the feet and cause a thick- 
ening of the epidermis which results in corns. But 
injuries to the bones and joints come from shoes 
that are too tight. The toes especially suffer. If 
the shoe is too short, the second toe is bent under 
at the end, its second joint is humped up and a 
corn often develops. In a short time this results 
in a deformity called a hammer toe. Narrow shoes 
are likely to crowd one toe, especially the great toe, 
over its neighbor. This extreme outward bending 
of the great toe makes the joint prominent. The 
joint then bears the pressure of the shoe, and a 
bunion, an unnatural growth of fibrous tissue and 
of bone, is the result. 

High heels throw the weight of the body forward 
upon the toes, crowding them into too narrow 
quarters. This results in their deformity, and 
sometimes in "flat foot." 



BONES AND JOINTS 4 j 

The bones of the fool and ankle are arranged in 

the form of an arch, with the heel at one end and 
the ball of the foot at the other. The tibia, sup- 
porting the weight of the body, rests on the top 
of the arch. The arch is elastic, and gives at each 
step, making a spring which decreases the jar on 
the body. A weak arch sometimes loses its spring- 
iness and settles down. This is called "flat foot." 
It causes pain in the foot and leg while standing, 
and produces an awkward gait. 

Most injuries to the feet can be remedied. 
Proper bandages, supports, and exercises will do 
much for a flat foot. The skin over a bunion can 
be cut open and the bony growth chiseled off. 
Crooked toes can be straightened. Corns can be 
softened and removed. But the sensible thing to 
do is to take such good care of the feet that such 
injuries and deformities never come. 

The shoe should fit just right — neither so tight 
as to bind nor so loose as to chafe. The lacing 
over the instep should be snug so that the toes do 
not push against the end of the shoe. The toe- 
particularly should have plenty of room, both at 
the sides and end. The heels should be low; 
rubber makes a comfortable, easy heel. If a shoe 
that is large enough presses uncomfortably on some 
part of the foot, have a second pair and change 
daily. Each pair will fit somewhat differently, and 
each joint, muscle, or spot of -kin made uncom- 



48 PHYSIOLOGY AND HYGIENE 

fortable by one pair will probably be rested by the 
other. 

Walking is one of the most convenient and 
healthful forms of recreation, but tender and de- 
formed feet discourage exercise in the fresh air. 
If the feet get tired, bathe and rub them daily or 
oftener. Watch for corns and ingrowing toenails, 
and attend to them as soon as they appear. A 
great deal of nerve-racking pain may be avoided 
by caring for the feet. 

Each pupil should make his own summary of this and subse- 
quent chapters. 



CHAPTER IV 
MUSCLES 

In this chapter you will study how muscles do 
their work, how differently the many kinds of 
muscles act, and how you can preserve their power 
and increase their efficiency. 

Function. All motions of the body and of its 
organs are produced by muscles, and this work i^ 
their main but not their only function. The mus- 
cles fastened to the skeleton are composed of long 
fibers which become shorter and thicker in con- 
traction, thus pulling on the bones to which they 
are fastened. Their force is always exerted in 
pulling, never in pushing. Even when we make a 
thrust movement, as in striking forward with the 
fist, the muscles employed pull on a set of levers — 
the arm bones. When the muscles relax they exert 
no force. 

Limb muscles. While the left arm hangs re- 
laxed, feel with the fingers of the right hand the 
muscles of the upper arm. With a string or a tape, 
measure the circumference of the arm. Bend the 
arm at the elbow vigorously; now feel the con- 
tracted muscles and measure the circumference of 
the arm. 

49 



50 PHYSIOLOGY AND HYGIENE 

i. Is the contracted muscle softer or harder, longer or 
shorter, thicker or thinner than the relaxed muscle? 

2. Bend the fingers of the left hand vigorously several 
times ; with the right hand feel for the contracted mus- 
cles. Where are they? 

3. Where can you feel the tendons (cords) through 
which these muscles make their pull on the fingers ? 

4. While the fingers are closed, bend the wrist forward. 
Where are the muscles that control the bending? 

5. Bend the wrist backward; where are the muscles 
that control this motion ? 

6. Why should the muscles be so far away from the 
parts moved? 

7. Where are the muscles (biceps) that bend the arm 
at the elbow ? 

8. Where are the muscles (triceps) that straighten the 
arm at the elbow? If the hand is moved against a 
resisting object the muscular contraction will be more 
vigorous and so more evident. 

9. As you sit, lift the toes from the floor, letting the 
foot rest on the heel. Where are the muscles that do the 
work ? 

10. Raise the heel from the floor, resting the foot on 
the toes. Where are the muscles that do this work ? 

Amount of force. The bones of the limbs are 
levers through which the muscles work. Figure 10 
illustrates the mechanical principle at the elbow 
joint. The tendon of the biceps is fastened to the 
forearm at p, the hand is at w, and the humerus 
at f. The distance represented by pf is about an 
inch and that by wf is about fifteen inches. There- 
fore to raise a weight of 10 lbs. in the hand, the 



MUSCLES 



51 



muscles would have to contract with a force of 
150 lbs. The triceps tendon is fastened at p', abovt 
Yi inch from f. To straighten the arm against a 
resistance of 10 lbs. at the hand, the triceps would 
have to contract with a force of 200 lbs. 




Fig. 10. To illustrate the leverage of the forearm, p — inser- 
tion of the biceps, p' — insertion of the triceps, f — the end of the 
femur, w — the weight to be lifted. 

The arrangement of the bones and muscles at 
the other limb joints is similar to that at the elbow. 
These muscles always work at a tremendous disad- 
vantage of power. To compensate for this, the 
muscle contracting through a fraction of an inch 
can produce a motion of several inches at the end 
of the bone it moves. 

1. A man of ordinary strength can bend the elbow with 
a weight of 40 lbs. in the hand. This would require a 
biceps contraction of how many pound-? 

2. Draw a straight line 15 inches long, and letter the 
ends F and W. One inch from F make a dot one-half 



52 PHYSIOLOGY AND HYGIENE 

inch above the line. From the point F draw through this 
dot another line equal to the first and letter its free end 
W. The distance WW is the distance the hand moves 
when the biceps contracts one-half inch. 

3. Make a diagram to represent the movement of the 
hand when the triceps contract. 

Position of limb muscles. Is the position of the 
leg muscles such that the swing of the leg in walk- 
ing carries it backward and forward much or little? 
Compare with the horse. Which animal has legs 
better suited for running? How would the effi- 
ciency of the hand be changed if the muscles that 
work the fingers were in the hand instead of in the 
forearm? 

Head and trunk muscles. 

1. Rest the forehead against the hand and, while the 
hand resists, try to move the head forward. With the 
other hand feel the contracted muscles and determine in 
what part of the neck they are located. 

2. Try to move the head backward against resistance. 
Where are the contracting muscles located ? 

3. Set the teeth together and bite hard. Where can 
you feel the muscles contract? 

4. Using a mirror, where can you see them ? 

5. Find the muscles used in moving the shoulders for- 
ward and downward ; in shrugging the shoulders ; in rais- 
ing the arm. 

6. Lean lazily forward against your desk and feel the 
muscles in the small of the back. While your hand is 
pressing your back, bring the body to an erect position. 
Where do you feel the muscle contract? 




1, occipito-frontalis 

2, temporal 
.".. mast 

4. orbicularis oris 
.">. platysma myoides 
• ;, it( mo-mastoid 
7, deltoid 

eps 

a, triceps 

10, brac-hio-radialis* 



11, pectoralis major 

12, Berratua anterior 

13, rectus abdominis 

14, obliquus externns 

16, sartnrius 

i»;, rectus temoris 

18, tibialis anterior 

19, extensor <ii^ r > • 
torum longus 

20, gastrocnemius 

21, soleu8 



Fig. ii. The superficial muscles of the body, appearing when 
the skin is removed. Some of the deeper muscles are larger and 
stronger than those here shown. Make the named muscles con- 
tract in your own body, and see what work each do 



54 PHYSIOLOGY AXD HYGIENE 

7. From lying flat on the back, ris~ to a sitting posture. 
Where can you feel muscles contract ? 

Examination of muscle. Examine a piece of 
stringy meat with a little fat in it. 

1. What three colors of tissue do you see in the speci- 
men? Which is muscle? Which is fat? Which is con- 
nective tissue? 

2. Pick some of the muscle to pieces with a pin or with 
your finger nail. About how large are the smallest fibers 
into which the muscle splits? 

3. Compare the thickness and strength of the sheath 
(perimysium) which envelops the large piece of muscle 
with that which covers the small piece. 

4. Pull the tendonous connective tissue. Does it stretch 
like. rubber? If it were other than it is why would it 
be unsuited to the work it has to do? 

5. Sketch a bit of the cross section of the muscle to 
show the arrangement of the little bundles. 

Classes of muscles. Microscopically the muscle 
you have examined has the structure shown in 
Figure 12A. It is called a striated muscle, from 
the Latin word stria, meaning furrow. Observe the 
location of the nuclei. Around each fiber is a 
delicate membrane and around each group of fibers 
a stronger membrane. The common muscles of 
the body are striated, but in the wall of the stom- 
ach and intestine, in the wall of the veins and 
arteries, in the iris of the eye, and some other 
places we find non-striated or smooth muscles. 
Observe the shape and size of the cells shown in 



55 



Figure 12Q. 



MUSCLES 
This is non-striated or smooth 



muscle. 

A third class of muscle is found only in the 
heart. See Figure 12B. Has this muscle striae 
Muscles of the first class are usually large and 
bunchy, and are fastened to hones. They contract 
all at once, and 
are partly or com- 
pletely under the 
control of the will. 
Non-striated mus- 
cles are in sheets, 
around cavities. 
They contract one 
part after another, 
rather slowly, and 
they are usually in- 
voluntary. To get 
an illustration >>f the 
action of a smooth 
muscle, place your 
neighbor so that he 
will face a bright 
light. Hold your hand an inch or two before his 
rye-. SO a- to shade them, \v\ ^< 1 that you can 

them well. Watch the pupils change as yon 
remove your hand. The motion is produced l>j 
muscles in the iris. 

Nerve control. The common striated muscles 




Fig. 12. Muscle fibers, A. portion 
of a striated fiber; the entire fiber 
may be an inch or more long, and 
1 100 ' >f an inch wide. 

A' shows a more high!) magnified 
filler, with the ending 01 the nerve 
which stimulates it. Are the nuclei 
more or less numerous at the nerve 
ending than at other plao 



56 



PHYSIOLOGY AND HYGIENE 



are altogether under the control of the nerve sys- 
tem. They lie relaxed until they receive a stimulus 
from a nerve, then they contract, gently or vigor- 
ously, according to 
the stimulus. The 
skill that comes 
with practice is the 
result of the devel- 
opment of the con- 
trol of the nerve 
system rather than 
of the muscles 
themselves. If two 
men have muscles 
of the same size, 
one may be much 
stronger because 
his nerve battery is 
more powerful. 
Athletic endurance 
trials are tests of 
the nerves that con- 
trol the muscles. 

The smooth mus- 
cles and the heart 
muscles are large- 
ly, but perhaps not 




B, fibers of heart muscle, magni- 
fied about as A. Are the fibers 
longer, or shorter, than common 
striated muscle fibers ? Are they 
wider, or narrower ? Do they branch ? 
The , empty spaces between cells 
shown in the figure result from 
pulling the cells apart ; in life the 
cells are tight together. 

C, smooth or non-striated fibers. 
Each cell has a single nucleus. How 
different from in B do these cells 
join? They are about %oo of an inch 



long, and Mooo of an mcn wide 
completely, under nerve control. 

Wear. In muscular contraction, nerve cells and 



MUSCLES 



57 



muscles both are oxidized, forming carbon dioxide, 
water, and nitrogenous waste. A good blood cir- 
culation is needed to remove the products of oxida- 
tion and to bring food and oxygen for rebuilding 
the used protoplasm. 

Heat. You are familiar with the fact that mus- 
cular activity produces heat. In warm weather 
the amount of work we can do is restricted by the 
rise in the temperature of the body. We must not 
produce heat faster than we cati get rid of it. In 
cold weather, however, the heat of muscular con- 
traction is a very welcome addition to the tem- 
perature of the body. In fact, if the temperature 
gets too low the muscles are set in motion to 
produce heat by shivering. 

Need of exercise. Commonly we do not under- 
stand how necessary to our health is muscular 
activity, and we frequently neglect taking adequate 
exercise. The human race has developed under 
conditions which have demanded strenuous phys- 
ical exertion. To get food and to escape his ene- 
mies, to meet the demands of the chase and of war, 
man became fleet of foot, supple of body, and 
strong of arm. The great majority of mankind 
-till earn their livelihood by physical labor. The 
large muscles, which most men require in their dail) 
occupation, need activity, and if those of us who are 
cooped up in offices, schools or shops, with no call 
for large muscular activities, neglect to find some daily 



58 PHYSIOLOGY AND HYGIENE 

means of exercise, we must pay the penalty. We 
probably do not know all the ways in which muscular 
activity benefits the body. We do understand some 
of the details of our need of exercise, and we shall 
now consider them. 

Muscular development. For the growth of the 
muscles themselves it is necessary that they be 
active. Boys and girls generally are disposed to 
physical activity, but some young folk as well as 
adults do not realize how necessary to growth is 
activity. Normal young persons have within them 
a force that drives them to move about. It is 
impossible for a healthy child to keep still. The 
young of all the common animals have the play 
instinct. Puppies and kittens tumble one another 
about, and colts and kids race and jump, insuring 
the exercise necessary for their muscular growth 
and for the development of the nerves that control 
the muscles. This principle is a condition of 
healthy vigor throughout life. 

Exercise and respiration. Active muscles re- 
quire a large quantity of oxygen, and produce 
much carbon dioxide. The respiration must con- 
sequently be rapid to bring in the oxygen and take 
out the carbon dioxide. It is almost impossible to 
develop a strong chest with good lung capacity if 
one does not take vigorous exercise. The w r elfare 
of the whole body, as well as of the muscles, is 
promoted by the improved respiration. 



MUSCLES 50 

1. Compare the rate of your breathing when at resl 
and when physically active. 

2. In which condition do yon till your lungs most com- 
pletely ' 

Exercise and circulation. It is necessary for the 
proper growth of the heart muscles and for the 
strengthening of the organ to meet the severe de- 
mands made upon it, that it be frequently exer- 
cised vigorously. This is best done by the vigorous 
activity of the whole body. The contraction of a 
muscle squeezes out of it the sluggish lymph and 
the blood that is slowly moving through the blood 
tubes, and makes room for fresh blood. Thus the 
active muscle cells are bathed with a quickly-mov- 
ing, fresh fluid, and the circulation of the entire 
body is invigorated by the exercise. 

Exercise and heat. \Ye have learned that the 
chief source of heat in the body is the oxidation 
that occurs in muscular contraction. On a cold 
day a person of vigorous muscular development in 
light clothes is kept comfortable by the heat pro- 
duced within his body, while his thin-muscled 
neighbor shivers in his heavy wraps. We say that 
our fingers and toes, our ear< and nose get cold 
because our blood circulation is not brisk enough. 
The way to ha\e a circulation suited to our needs 
is to train the heart and blood vessels by exercise 
to respond to the demand made upon them. 

Effects of muscular activity. The beneficial ef- 



60 PHYSIOLOGY AND HYGIENE 

fects of muscular activity are more far-reaching* 
than the influences on growth, respiration, circula- 
tion and temperature. The parts of the body are 
so intimately connected that whatever influences 
one part, influences all. The whole body responds 
to the improved tone of well-exercised muscles. 
The mind becomes more alert and vigorous. These 
far-reaching effects may be the result of good res- 
piration or circulation, or both. They are at least 
the result of suitable exercise. 

Play. The spirit in which we exercise is very 
important. To produce the best results, the activ- 
ity should not be dull work, but should in part be 
play, or done in the spirit of play. Play is usually 
a free and much varied activity, bringing into 
action many muscles; while work is often a dull 
repetition of restricted motions. The enthusiasm 
with which we enter into play is a very important 
element of its value. If we could engage in our 
physical work with the same enthusiasm that we 
carry into play, we should get much more work 
done and find it less exhausting. 

Intensity. Exercise should be vigorous. A boy 
or girl in poor health or unaccustomed to exercise 
may find a little walk sufficient, but for one in his 
normal condition the activity should call for strong 
contraction of the muscles, and should be con- 
tinued until he is well tired — fatigued, but not ex- 
hausted. When the muscle cell breaks down more 



MUSCLES 6l 

rapidly than it is rebuilt by the food and oxygen 
of the blood, it becomes exhausted and rapidly 
loses its power to work. Exhaustion is less rapid 
when the blood has a good food supply, but it 
finally comes if the activity is too long continued. 
No muscle should be held in continuous vigorous 
contraction for more than a few* seconds at a time. 
The ideal exercise involves a greai variety (^\ move- 
ments, some rapid some slow, some gentle, some 
strenuous, with periods of rest interspersed. Think 
of several forms of work and of play that fulfil 
these requirements. 

Serious injury may result from too strenuous ac- 
tivity, especially in growing youth. The heart is 
overworked, stretched, weakened for life in a very 
large percentage of the athletes who engage in 
football, boat and marathon contests. It is just as 
important not to over-do as not to under-do the 
vigor of exercise. 

Food. Careful experiments in measuring the 
force of a muscle'- contraction show that the first 
of several repeated motions i> the strongest. After 
a few contraction- the force diminishes very rap- 
idly. Rest and food, however, re-tore the vigor of 
the muscle. In a general way we understand that 
we cannot work unless we eat, but we do not 
usually appreciate how quickly a muscle responds 
to abundance or scarcity of food in the blood. I he 
omission of a meal has been found to decrease the 



62 PHYSIOLOGY AND HYGIENE 

force of muscle contraction about one-half. The 
practice of going without breakfast may be helpful 
to some diseased stomachs, but the body needs 
food for the work of the day, and the ordinary boy 
or girl should prepare for the clay by taking a sub- 
stantial breakfast. 

Alcohol and narcotics. The general effect of alco- 
hol, in small or large quantities, is to decrease the force 
of muscular contraction. It is true that the effect of a 
small dose of alcohol on the muscle is, under certain 
conditions, stimulating; that is, the muscles con- 
tract more quickly and with greater force. But 
this effect soon passes, and the muscles have less 
strength than they had before. The habitual use 
of alcohol slowly weakens the muscles. They do 
not assimilate food nor do they grow so well when 
alcohol is present. The stronger the liquor and 
the more it is used, the worse the effect. In ex- 
treme cases some of the muscle cells degenerate 
into fat. People who use alcohol and tobacco to 
excess have very imperfect control of their mus- 
cles. Muscular contraction is deranged chiefly by 
the effect of the drugs on the motor nerve centers. 



CHAPTER V 

THE NERVE SYSTEM 

The nerve function. There are some tiny single- 
celled animals which are composed of a continuous 

mass of protoplasm. If one side of such an animal 
is touched, all the protoplasm contracts, drawing 
the animal away from danger. There must be 
some way in which the protoplasm touched takes 
cognizance of the touch and communicates its dis- 
covery to all the protoplasm of the animal. Some- 
what larger animals composed of hundreds of cells, 
yet still very small, respond to a touch in the same 
way. In them the protoplasm that feels the touch 
must send its message through other cells to all 
parts of the body. Any cell of these tiny creatures 
seems to have the power of receiving impressions 
from the outside world and of communicating them 
to other parts of the body. This power is neces- 
sary for putting the animal into relation with the 
world around him, for enabling him to get food and 
escape clanger, and also for correlating one part 
of the body with another. This function, which 
we may call irritability, is possessed by all the pro- 
toplasm in the lowest animals. You will learn in 

this chapter how the same need of relation to the 

63 



6 4 



PHYSIOLOGY AND HYGIENE 



outside world and of correlation within is more 
fully met by the highly developed nerve system 
of man. 

The neuron. The unit of structure in the nerve 




Fig. 13. Diagrammatic rep- 
resentation of a neuron. d, 
dendrites ; a, axon, which is 
covered most of its length with 
a sheath; e, end of nerve in 
muscle, etc. 




Fig. 14. A highly developed 
neuron, magnified 20 or 30 
times. Only the beginning of 
the axon is shown, d, den- 
drites; A, axon. 



system is the neuron. It consists of a large cell, 
1/200 of an inch in diameter or smaller, and the 
projections growing out from it. One is shown in 



THE NERVE SYSTEM 65 

Figure 14. Compare it with the diagram in Figure 
13. The protoplasm projections, called dendrites 
(tree-form), are for receiving currents from other 
neurons. Observe the number on a single cell. 
The neuraxon or nerve liber is a prolongation of 
the cell protoplasm which enables it to send cur- 
rents to different parts of the body. Each cell has 
but one nerve fiber, sometimes only a fraction of 
an inch in length, and sometimes two or three feet. 
Its diameter is very slight. Along its course 
through the body it is, in most cases, covered by a 
tube composed of cells encased in a thin membrane. 
The fiber gives off no branches where it is covered, 
but near the ends, where the covering is absent, it 
may branch, sometimes abundantly. The nerve cells 
are grouped together in various parts of the body, as 
in the brain and spinal cord, and each group of cells 
is called a ganglion. 

The nerve. A nerve is a bundle of cell projec- 
tions, neuraxons, few or man}' in number, together 
with connective tissue and blood-vessels. It is like 
a telegraph cable of many wires bound together, 
each going to its own destination and insulated 
from its neighbors. The nerves give off many 
branches, but these are merely fibers separating 
from the main group. The fibers themselves do 
not branch. Figure 15 shows a cross section of a 
nerve. At the outside are strengthening connective 
tissue and blood vessels. Each fiber appears as a 



66 



PHYSIOLOGY AND HYGIENE 



small circle in whose center is the axis or active 

part, the outgrowth from the cell. 

Method of action. 
The following ex- 
ample will illustrate 
the way in which the 
nerve system acts : 
A fly alights on your 
hand. From a touch 
organ in the skin be- 
neath him a current 
is sent over a nerve . 
fiber or neuron whose 
cell is located in a 
spinal ganglion. See 
Figures 16 and 21. 
This neuron passes 
the current on to a 




Fig. 15. Cross section of a 
nerve, magnified. The mem- 
branous connective tissue at the 
outside is represented quite dia- 
grammatically. The nerve fibers 
are in bundles, between which are 
connective tissue and blood ves- 
sels. The nerve is represented 
shrunk away from its covering, 
which in life it fills. 



central cell in the 
spinal cord. The receiving cell undergoes a chem- 
ical change; some of its protoplasm breaking down 
into less complex substances, carbon dioxide, water 
and nitrogenous waste. It sends a current out to a 
motor cell 1 which in turn sends a current to a 
muscle. The muscle contracts and produces a 
motion to drive away the offending insect. 

This is a nerve action reduced to simple terms. 
In this action there are involved, first, a neuron 
reaching from the touch organ to the spinal cord. 



rill- NERVE SYS I l-'.M 



67 



with its cell located in the spinal ganglion; second, 

one or more central neurons which receive the cur- 
rent and communicate with a third, the neuron 
carrying the current out to the 
muscle. We should not expect 
to find the process actually so 
simple. Instead of a single cur- 
rent over one fiber, there are sev- 
eral currents over several fibers 
going from the skin to the spinal 
cord. The receiving cells may 
send currents through a compli- 
cated network of correlating 
neurons which finally stimulate 




the motor cells to discharge into 



Fig. 16. A dia- 
grammatic repre- 
sentation of a por- 
tion of the spinal 
cord. The size of 
the nerves and 
cells is greatly 
exaggerated. G — a 
cell of the spinal 
ganglion ; there- i- 
one central cell, 
and at the left are 
-ix motor cells. 



the muscles. The muscles which 
produce any considerable motion 
would require for their con- 
traction the stimulus of a whole 
battery of nerve cells. 

Reflex, voluntary, and automatic action. An ac- 
tion like that just described, in which a sense organ 
sends a current to the spinal cord or to some minor 
ganglion that immediately stimulates the muscle, 
is called a reflex action. It is the quickest and most 
economical response we can get to an outside stim- 
ulus. In some reflexes, especially in lower animals, 
it is thought that sensory nerve fibers communicate 
directlv with motor cell dendrites without the in- 



68 



PHYSIOLOGY AND HYGIENE 



tervention of central neurons. In contrast with 
this is, first, the voluntary action, in which the 
receiving cells communicate with^the brain which 
issues the motor current; and, second, the auto- 
matic action, which is unlike the reflex in that it 
arises from an internal condition instead of from 
an external stimulus. 



EUSTACHIAN 
TUBE 



CEREBELLUM 




ESOPHAGUS 



Fig. 17. Left half of the head and neck, median section. 
Notice the situation and chief parts of the brain. 

Be prepared to tell of examples of each of the 
three kinds of action. 

The nerve current. What the nerve current is, 
which goes along the nerve from sense organ to 



THE NERVE SYSTEM 



69 



cell, from one cell to another, and from cell to 
muscle or gland, no one seems to know. It is some- 
thing like an electric current, but while the electric 
current is practically instantaneous over a wire, the 
nerve current travels through the nerve at the rate 
of about ninety feet per second. Pressure on a 
nerve will prevent the passage of the current, while 




Fig. 18. Brain from below, showing the nerves numbered. 
1 — smell, 2 — sight, 8 — hearing, g — taste. The others supply mus- 
cles, skin, teeth, etc. 

the axis of the nerve fiber, unlike the electric wire, 
is presumably worn by its activity. The cells which 
surround it are thought to supply it with food and 
gen and perhaps to assist it in carrying the 
nerve current, but their function is not well 
understood. 



70 



PHYSIOLOGY AND HYGIENE 



The brain. For the study of the brain, cut a 
calf's head into right and left halves. This can 
easily be done by splitting the nasal cartilage with 
a knife and by sawing carefully through the bones. 
Then the hemispheres of the brain should be care- 
fully separated and the cerebellum, medulla, etc., 

cut exactly through 
the middle with a 
sharp knife. 

i. Notice the medulla 
oblongata at the large 
opening in the base of 
the skull. Its downward 
continuation is the spin- 
al cord. What color is 
it ? How does it feel ? 

2. Trace the medulla 
forward. Does it lie 
along the floor, or in the 
upper part of the cra- 
nial cavity? 

3. The cerebellum lies 
just above the medulla. What color and how thick is 
the pillar or stem that fastens it to the base of the brain? 

4. What two colors appear in the cut surface of the 
cerebellum? Which color is in the middle of each lobe? 
Which at the margin ? 

5. The large portion of the brain remaining is the cere- 
brum. What part of the cranial cavity does it occupy? 

6. The band of fibers, corpus callosum, connecting the 
right with the left hemisphere was cut in dividing the 
brain. What color is it? 




Fig. 19. Cross section of a 
small lobe of the cerebellum, 
highly magnified, showing the ar- 
rangement of the nerve cells, their 
dendrites and axons. 



THE NERVE SYSTEM 



7* 



7. Make a cut in the cerebrum. Tissues of what two 
colors do you see? Which is in the middle of the lobe? 
Which is at the surface? 

8. The folds in the cerebrum and cerebellum increase 
the amount of which tissue — the white or gray? The 
gray contains the cells, the white the connecting fibers. 

9. Lift the brain partly out of its setting, but do not 
break any threads : the white strings extending from it 
are nerves. To what part of the brain are they attached? 

10. Is the part of the membranous covering of the 
brain which adheres to the skull tough or tender? Is it 
smooth or rough inside? Does this part dip into the 
furrows of the cerebrum? into the deep notch between 
cerebrum and cerebellum? 

11. Does the delicate membrane which adheres to the 
brain dip into the convolutions ? 

12. Make a general sketch showing the parts of the 
brain and the nerve attachments. Make a sketch of a 
section through the cerebrum, and another through the 
cerebellum, showing the arrangement of the white and 
gray matter in the lobes. 

Localization of function. The nerve tissue in the 
large lobes of the brain is composed of central 
neurons and fibers communicating with them. The 
cells of the peripheral neurons, those which bring in 
the currents and carry them to muscles, to glands, 
or to outlying ganglia, arc located along the spine 
or in small ganglia in the head. The brain receives 
current- from all the sense organs of the body, and 
ds out currents to all the voluntary muscles. 
One special part of the brain is the sight center, 



72 PHYSIOLOGY AND HYGIENE 

another part the hearing center, another the taste 
center, and so on. See Figure 20. Nerves of touch 
from the hand come to one part of the brain, from 
the foot to another part, from the chest and the 
back to still other parts. In like manner the motor 
centers are localized, cells of one definite area send- 
ing currents to one muscle or set of muscles, and 
those of another area to other muscles. The areas 
of both sensory centers and motor centers are not 




Fig. 20. Diagram of sensory and motor areas in the brain of 
a monkey. 

altogether distinct from one another, but overlap 
at the margins and sometimes one area largely 
covers another. The frontal portion of the cere- 
brum, which is not a motor or a sensory center, is 
thought to be the region especially involved in 
thinking, though other centers also take part in 
this activity. It receives currents from other cen- 
ters and through a complicated network of cells 



fHE NERVE SYSTEM 



73 



and connecting fibers, in a way that has not been 
thoroughly worked out, it establishes relationships 
— and we have ideas, thoughts, and emotions. 

Spinal cord anatomy, For the study of the spinal 
cord, get about four inches of sheep neck. Roughly 
trim off the muscles and cut out the dorsal arches 
of the vertebrae by sawing along each side. If the 
material is not fresh, the cord may have shrunk; 




Fig. 21. Diagram of a portion of the spinal cord, from behind, 
gn — spinal ganglion. The cells, in the gray matter, and the 
tibers. in the surrounding white matter, are disproportionately 
magnified. Note that some incoming fibers run to the gray 
matter and some send branches which run in the white matter 
lengthwise of the cord. 

it should fill' the canal snugly. Observe whether 
each spinal nerve joins the cord by a single strand 
or by several strands. Each nerve has tw r o roots, 
not easily seen without a more careful dissection 
than you have been asked to make. The ventral 
root is composed chiefly of fibers which carry cur- 
rents out to muscles, and is therefore called the 
efferent or motor root. The dorsal root carries 
currents from the touch organs to the cord and is 
hence called the afferent or sensorv root. The 



74 PHYSIOLOGY AND HYGIENE 

cells, to and from which the fibers of the dorsal root 
run, are located in the spinal or dorsal ganglion. 
The gray matter of the cord contains the gan- 
glion cells; some, along the dorsal side, for receiv- 
ing currents from the spinal (dorsal) ganglia and 
for communicating with other cells of the cord or 
of the brain ; and some, along the ventral side, for 
sending out currents to the muscles, glands, and 
small ganglia. The nerve fibers compose the white 
matter of the cord. They carry currents from one 
spinal cell to another and connect the cells in the 
brain with those in the spinal cord. 

1. Where is the spinal ganglion? See Fig. 21. 

2. Is the outer membrane covering the cord tough or 
tender ? 

3. Describe the inner membrane. 

4. The membranes covering the cord are continuous 
with the corresponding membranes of the brain. Does 
the cord itself feel soft or firm? 

5. Tissues of what two colors appear in the cut end of 
the cord? 

6. Sketch to show the relative positions of these tis- 
sues. A hardened and stained specimen will show them 
better than the fresh material, and should be used if 
accessible. 

Function of the cord. The spinal cord acts as a 
local center, thus relieving the brain of a great deal 
of work. It controls, largely, the digestive organs 
and the blood system. It receives the incoming 
nerve currents from the skin, joints, and muscles 



THE NERVE SYSTEM 



75 



below the head, sends on to the brain the messages 
which need the attention of that center, and attends 
to the minor matters it- 
self, sending- stimuli to the 
muscles for the necessary 
activities. Reflex actions 
in the body below the head 
are produced through the 
spinal cord and medulla. 
Thev do not involve the 
brain proper. 

Sympathetic system. 
The plan of controlling 
involuntary activities by 
local ganglia is further 
carried out through what 
is sometimes called the 
sympathetic system. Fig- 
ure 22 is a diagram repre- 
senting one of the two 
chains of ganglia situated one on each side of the 
spinal column. It includes also three groups of 
ganglia and a network of nerves situated in about 
the middle line of the body, and connected with 
the two chains and with the spinal cord and brain. 

Nerves run from the sympathetic centers to the 
organs of the chesl and the abdomen, and to many 
of the arteries in the skin, the glands, and the 
muscular parts of the body. 




PELVIC 
PLEXUS 



Fir,. 22. One of the two 
sympathetic nerve chains, 
and the median ganglia, 
seen from the side. 



j6 PHYSIOLOGY AND HYGIENE 

1. Name the organs which the diagram shows are in 
part supplied with nerves from the sympathetic center. 

2. With how T many ganglia is the heart plexus con- 
nected ? 

3. Where is the solar plexus in relation to the dia- 
phragm ? 

4. With how many ganglia in the main chain does the 
solar plexus seem to be connected? 

5. With what besides the ganglia of the main chain is 
the plexus in the pelvis connected ? 

6. Does every ganglion send off nerves (at the left 
Fig. 22) to join the spinal nerves? 

Habit. The first time we try to do a thing the 
movements are slow and awkward. It is with dif- 
ficulty that the nerve currents are directed along 
the desired channels. With each repetition of the 
motion the nerve currents move more easily, till 
they come to flow with the utmost ease and swift- 
ness along the well established channels. It is so 
not only with muscular movements but also with 
thoughts and feelings. When you attack a new 
kind of problem in algebra the nerve currents do 
not move smoothly along the new road, but when 
you have solved a few problems of this kind, the 
nerve currents have established their course and 
the work is less difficult. Nerve currents always 
prefer the established routes. The actions, 
thoughts, and feelings to which we have become 
accustomed are our habits. They require little 
effort or attention. Habit is deep-seated in the 



THE NERVE SYSTEM yy 

nerve system, and is not easily altered. How im- 
portant it is, then, to establish good habits instead 
of bad! During conscious life we must continually 
think and act in some sort of way. If we are not 
forming habits of right thinking and right acting, 
we must be forming wrong habits. The formation 
of good habits prevents the formation of bad ones, 
and the only sure way to correct a bad habit is to 
form a good one to take its place. 

Education. Education consists in establishing 
desirable nerve routes so that the mind and muscles 
act quickly and easily to accomplish the things we 
desire. Xo one can educate you. Filling your 
mind with facts is not education. The facts are 
things to be used. Schools, teachers, and books are 
helps, but you must develop your own powers, 
acquire habits of accurate thought and desirable 
conduct by your own persistent, careful practice. 
The greater your activity and the wider its range, 
the broader and more thorough will be your 
education. 

Stimulants and narcotics. The effect of stimu- 
lants and narcotics upon the nerve system is greater 
than upon other tissues. Since this system con- 
trols the muscular, and, at least to some extent, the 
secretive and assimilative activities, these drugs 
exert an influence over the whole bod}-. Alcohol 
affects the various nerve centers in different ways. 
The centers that control the blood circulation re- 



78 PHYSIOLOGY AND HYGIENE 

spond quickly to small quantities of alcohol. The 
heart beats more rapidly and there is an increase in 
the blood supply, especially to the brain, skin, and 
mucous membrane. This makes the thoughts more 
lively for a time. The skin becomes red and the 
mucous membrane more active. A larger quantity 
of alcohol depresses the higher nerve centers. The 
judgment, which sits in control over all our volun- 
tary activities, is impaired, the reins of control are 
loosened, the tongue runs riot, the actions are ludi- 
crous or vicious, as the ungoverned imagination 
suggests. A still larger quantity of alcohol deadens 
both motor and sensory centers. The body has 
little feeling and moves sluggishly and uncertainly. 
The occasional use of small quantities of alco- 
holic liquors sometimes produces no noticeable per- 
manent effect on the nerve system. But to the careful 
experimenter, it has a very noticeable temporary effect. 
It decreases markedly the quickness and the power of 
both mental and muscular actions. And in the ordi- 
nary temperate drinker the nerve centers are perma- 
nently dulled; they respond less promptly and less 
vigorously to the calls made on them. The habitual 
excessive use of liquor produces the chronic condition 
of exhausted and inefficient nerves, manifested in 
the shambling gait, thick speech, and bleary look 
of the old toper. The nerve trunks in hard drinkers 
are sometimes so diseased (neuritis) that they not 
only fail in their function but cause great pain. 



THE NERVE SYSTEM yg 

Saint Vitus Dance. Children sometimes suffer 
from St. Vitus dance, a twitching of the muscles 
due to perverted nerve impulses. Fatigue, lack of 
exercise, and germ-infected air are among its 
causes. A physician should be consulted when the 
symptoms first appear. With more hygienic living, 
the nerves usually regain their normal control of 
the muscles. 

Sleep. Plenty of sleep is necessary to a sound 
nervous system. During sleep the protoplasm of 
the nerve cells, which has become perceptibly 
shrunken and exhausted by the activities of the 
day, is restored to its fullness and strength. In the 
quiet of the country, a tired body drops into sound 
sleep early, and awakes in the morning with a fresh, 
vigorous nerve system. Dwellers in the bustling 
city, living under a higher nervous pressure, are in 
greater need of sleep, but are more tempted by the 
excitement and press of multitudinous duties to 
deny themselves the indispensable rest. Though 
people differ considerably in the amount of sleep 
they require, adults should have seven or eight 
hours a dav, and children nine or ten hours. The 
sleep should be quiet, not troubled by distressing 
dreams or broken by the mind's dwelling on the 
perplexing problems of the day. To this end the 
last half hour or so before retiring should be given 
U» relaxation. Students should do their hard work 
in the morning, and reserve the lighter work for 



80 PHYSIOLOGY AND HYGIENE 

evening. No study after nine o'clock, is a good 
rule. The boy or girl who digs at his lesson until 
eleven or twelve o'clock at night is pretty sure to 
be dull, irritable, and inefficient the next day. His 
nerve cells are not at their best. The best prepara- 
tion for mental or physical strain is a good sleep. 
Hygiene. The superiority of man to the lower 
animals is most conspicuous in his nerve system. 
It is precisely where civilized man is most devel- 
oped that he breaks down most easily. We live in 
what has been called an age of nervous prostration. 
The speculator watching the market, the society 
woman madly pursuing a program, and the scholar 
striving for honors or promotion, all are the fre- 
quent victims to the disease of the age. We should 
learn to relax, to rest. Some time each day should 
be given to quiet and meditation. The various 
sorts of mental healing often produce good only 
because they establish nerve quiet, and direct the 
thoughts away from self. One can live under good 
conditions of physical hygiene, and yet become a 
nervous wreck, if he is the subject of constant 
nervous irritation. Great minds cultivate poise and 
equanimity. We are wont to magnify the small ills 
of life, if there are no large objects to occupy us. 
One engaged in thoughts of science, government, 
or philosophy is not worried over his own petty 
affairs of life. The dignified pursuit of a worthy ob- 
ject in life gives tone and poise to the nerve system. 



CHAPTER VI 

CIRCULATION 

You already understand that the food prepared 
by the digestive organs, and the oxygen taken in 
through the lungs, must be distributed throughout 
the body, so that each cell shall receive its share ; 
and that the carbon dioxide and other products of 
oxidation must be removed from the cells. This 
work is done by the circulatory system. The essen- 
tial parts of this system are, first, a circulating 
fluid; second, an engine to make it move; and 
third, a system of tubes to convey it. This gives 
a three-fold division of the chapter. 

Blooi~i and Lymph 

The blood consists of cells called corpuscles, and 
the fluid in which they float. The corpuscles are 
of three kinds : the red corpuscles, the white cor- 
puscles, and the blood plates. The last named are 
so small and disappear so quickly in dead blood 
that little has been learned about them; they may 
'ragments of white corpuscles. 

Red corpuscles. The red corpuscles are shaped 
like coin-, thinner in the middle than around the 
rim. and are about i 35°° °t an ^ nc ' 1 ]U diameter. 

8l 



82 PHYSIOLOGY AND HYGIENE 

They are composed of protoplasm rather stiffer 
than that in most cells, and although they can be 
bent they spring back to their disc-like shape. 
Since the corpuscles are alive, that is, composed of 
protoplasm, they die of injuries, wear out, and must 
be replaced. They are not known to multiply by 
dividing, as most cells do, but are produced in cer- 
tain cells of the red bone marrow and in other 
places. The red color of the corpuscle is due to a 
substance, called hemoglobin, contained within the 
protoplasm. 

The hemoglobin performs the most important 
function of the red corpuscle, that is, to carry oxy- 
gen. When the blood passes through the lungs, 
all parts of it absorb some oxygen from the air in 
the lungs, but the hemoglobin makes a chemical 
combination with the oxygen and so is able to 
absorb many times as much as it could hold in sim- 
ple solution. As the blood circulates through the 
body distributing the oxygen everywhere, the 
hemoglobin goes through a reverse chemical 
change, giving up its oxygen to the surrounding 
fluids, which pass it on to the protoplasm in the 
cell. 

White corpuscles. There are several varieties of 
white corpuscles. They are fewer in number than 
the red, about one white to every six hundred red. 
They are colorless, larger in size than the red, and 
composed of more watery protoplasm. When they 



CIRCULATION 



83 




die they draw together into spheres and are usually 

seen under the microscope. In life they get 

about by a (lowing motion, changing their shape in 

such a way that one eorpnsele 

may take, in a few minutes, all 

the forms shown in Figure 23. 

I )f course the white corpuscles 

float along in the blood to all 

parts of the body, but they are J** %j*£* 

not restrained as the red are with- a— surface of the 

disc; b — edge; c — 
in the blood tubes. They are able in rouleau; d— a 
. 1 • n • colorless corpuscle, 

by their flowing movements to showing the four 

get through the walls of the capil- fo ' ms *! took 

B & [ within a few min- 

laries and move about almost utes, and the 

spherical form, 
everywhere in the body. They magnified less than 

►ngregate in large numbers wher- 
ever the tissue is injured, at wounds or sores, and may 
do some work in repairing the injury. Their most 
important evident function, however, is in destroying 
bacteria. | See page 225. ) This they do by flowing 
around the germs and by digesting and assimilating 
them. 

The plasma. Though not protoplasm, the 
plasma contain- all the elements that go to make 
u]) that fluid. It holds in solution almost every 
substance of the body that is soluble; it serves as 
a fluid to float along the corpuscles, and is the food 
of the protoplasm. The plasma readily oozes 
through the walls of the capillaries and gets into 



84 PHYSIOLOGY AND HYGIENE 

the minute spaces in the tissues. There we must 
change its name and call it lymph. 

The lymph. The white corpuscles and plasma 
form the lymph, which constantly bathes the cells, 
circulating slowly, bringing food and oxygen to 
the protoplasm and carrying away the products of 
oxidation. It is thus an intermediary between the 
cells and the blood vessels. Some of the lymph 
gets back into the blood through the walls of the 
capillaries and becomes a part of the plasma. The 
remainder is collected by a set of tubes called 
the lymphatics and carried back into the blood 
system. 

Coagulation. AY hen blood vessels are broken 
and the blood runs out into the spaces among the 
cells or escapes from the body, it soon coagulates or 
clots. It sometimes clots also w T ithin the vessels 
when they are injured. A ferment forms in the 
injured cells or in the dying corpuscles. It acts on 
the plasma, changing part of it into minute threads 
called fibrin. The fibrin threads extend through 
the mass of blood causing it to have the appearance 
of red jelly. The process is similar to that which 
occurs when sour milk gets thick. If the blood 
contains considerable lime salts it clots more 
readily. The fibrin threads soon contract, draw- 
ing with them the entangled corpuscles and form- 
ing a compact clot. The part of the plasma that 
has not changed into fibrin is squeezed out of the 



CIRCULATION 85 

contracting clot as a straw colored liquid called 
serum. The serum usually drains off or evaporates, 
leaving the stiff clot behind. The lymph clots in 
the same way as the blood, but since it has no red 
corpuscles, its clot is colorless. Sometimes the skin 
is scraped, not deep enough to cause bleeding, but 
so that the lymph oozes out and forms a clot, which 
dries to a colorless scab. The function of the clot is 
to plug up the wound and so prevent further bleed- 
ing. If the blood did not clot, a cut in even a small 
vein might drain away much of the blood and so 
be fatal. 

Blood Tube- and Lymphatics 

The arteries. The blood is carried from the 
heart by arteries. They are stiff, strong-w T alled 
tubes, the largest about the diameter of the thumb. 
From the larger tubes smaller ones branch off and 
subdivide, distributing the blood everywhere 
throughout the body. The blood is forced through 
the arteries by the contraction of the heart. We 
do not always appreciate the strength of the heart's 
contraction and the force with which the blood is 
pressed into the arteries. If a large artery were 
an inch in diameter, the blood in it would press 
inst an imaginary partition across it with a 
force of four pounds. To withstand this great 
pressure of blood, the arteries must have strong 
wall-; the walls must be elastic, to yield a little 
when the heart contract- and the blood comes with 



86 



PHYSIOLOGY AND HYGIENE 



most force, and to spring back when the pressure 
is less between heart beats. This strength and 
elasticity is obtained by a network of yellow elastic 
fibers which compose most of the wall of the large 
arteries. Beside the elastic fibers there are small 
non-striated muscles, and at the outside a web of 
inelastic fibers. The arteries are lined with a 
smooth membrane composed of a single layer of 



...VEIN 




NECTIVE TISSUE 4 
MUSCULAR COAT- 
ELASTIC COAT 
ENDOTHELIAL C 
ARTERY 




Fig. 24. Diagrammatic representation of the walls of blood 
vessels. In the side view the outer layers are cut away to 
expose the inner. 

flat cells edge to edge. The blood pressure in the 
large arteries is much greater than in the small, and 
so their walls are thicker. As the arteries get 
smaller there is a steady dimunition in the quantity 
of the strong fibers and muscles, until there are left 
around the lining membrane only a few muscle 
cells. When the tubes get still smaller, and there 
is no covering over the lining membrane, they are 
capillaries. 



CIRCULATION' 



87 



The capillaries. Almost everywhere in the body, 
making a network connecting the arteries with the 
veins, are the capillaries. Their diameter is about 
1/3000 of an inch ; their length averages about 
1 2$ of an inch, but they vary a great deal, some 
being several times as long as others. They are so 
close together that a fine needle could not be thrust 
into a tissue without destroying a number of them. 
Their walls are too thin to be measured. Describe 
the shape of the cells which make up the wall of a 
capillary. (See Figure 25.) 
The blood goes through the 
network of capillaries in an 
irregular course, at times re- 
versing its direction in some 
tubes, going now faster, now 
slower, but always from the 
greater pressure of the arter- 
ies to the lesser pressure of 
the veins. As the blood flows 
through the capillaries some of its plasma passes 
through the thin cells and becomes lymph. Some 
of the white corpuscles get through the cement 
between the cells and wander off in the lymph 
spaces, while the oxygen passes out to the proto- 
plasm that needs it. Moving in an opposite direc- 
tion,- carbon dioxide goes from the tissue into the 
blood, and some lymph and white corpuscles 
return. 




Fig. 25. Capillaries, 
much magnified. A — 

section ; B — surface 
showing cells. 



88 PHYSIOLOGY AND HYGIENE 

Veins. The function of the veins is to gather 
the blood from the capillaries and return it to the 
heart. The smallest veins are but little larger and 
stronger than the capillaries. From these the 
blood flows into successively larger tubes until all 
that in the lower part of the body is collected into 
the large trunk called the ascending vena cava, 
whence it flows to the heart. The walls of the 
veins are composed of the same tissue as the walls 
of the arteries, but since there is less blood pressure 
in the veins, the walls do not need to be so strong. 
The arteries are stiff like hose pipe, because of the 
large number of elastic fibers in their walls; the 
veins are soft and collapse when empty, because 
their walls contain only a small quantity of soft fiber. 

Valves. It would be easy to press the blood in 
the flabby veins back toward the capillaries, if it 
were not for the valves, little pocket-like folds of 
membrane in the lining of the veins. These valves 
have no power of motion in themselves. They lie 
passive in the blood current, and while the stream 
is moving toward the heart they are pressed 
against the sides of the tube, but when the stream 
starts to back up their free edges are caught and 
thrown out, opening the pocket and closing the 
vein. The venae cavae and veins surrounded by soft 
organs, as in the brain and the abdomen, have no 
valves. 

The arteries are without valves except at the 



CIRCULATION 



89 



heart. The blood pressure in the arteries is strong 
enough to keep the blood always moving forward, 
and the walls are so stiff that they are not easily 
compressed and the blood driven back. 

The lymphatics. The work of the veins in 
returning to the heart the circulating fluid is sup- 
plemented by the lymphatics. A 
large part of the plasma and of 

white corpuscles that passes out Fig. 26. Alongi- 
f - n r ,1 -11 • tudinal section of 

of the walls of the capillaries a vein w j t h va j vcs 
does not return into the capil- closec l- 
laries. It is collected from the intercellular spaces 
by the lymph tubes, brought into the lymph trunks, 
and finally back to the general blood circulation. 
The small lymph tubes were thought to be open 
at the end to the various cavities of the body and 
to the intercellular spaces, but recent studies seem 
to show that they are closed. Yet the contents of 
the intercellular spaces is readily taken up and car- 
ried off by the lymphatics, — bacteria and other 
minute particles as well as fluids. The lymphatics 
then perform a sort of scavenger function, picking 
up and removing whatever lies among the tissues. 
Here and there through the body lymph tubes con- 
verge into small centers called glands or nodes, 
from which other lymph tubes lead on toward the 
lymph trunks. The function of the glands seems 
not fully known. Some varieties of white corpuscles 
are produced in them, and the lymph is to some 



90 



PHYSIOLOGY AND HYGIENE 



extent filtered in passing through them. Most of 
the bacteria are caught, delayed, or destroyed, but 
some get through. Along the stomach and intes- 
tines the lymphatics pick up a portion of the ab- 
sorbed food. They are here called lacteals, because 
of the milky appearance of their contents while 
digestion is going on. 




Fig. 27. Diagram of capillaries and the beginnings of the 
lymphatics. A — arteries ; V — veins ; L — lymphatics. 

i. The main receiving center of the lymph system lies 
on which side of the diaphragm? See Fig. 28. It re- 
ceives the lymph from the lower part of the body. 

2. Describe the location of the trunk (thoracic duct 
or cysterna chyli) that carries the lymph from this recep- 
tacle to the vein. 

3. What vein does it join? 

4. At what place? 



CIRCULATION 



91 



RIGHT 

LYMPHATIC 

DUCT 



SUBCLAVIAN 
VEIN 



SUBCLAVIAN 
VEIN 




DIAPHRAGM 



RECEPTACULUM 

CHYLI 



Fir,. 28. Central lymph trunk (Thoracic duct), the nodes or 
glands and the tubes. For the positions of the veins, see Fig. 34; 
jugular vein from the head, subclavian from the arm. 



92 PHYSIOLOGY AND HYGIENE 

5. Just before the duct joins the vein it receives 
branches from what places? 

6. How is the lymph from the right side of the head 
and chest and from the right arm disposed of ? 

7. Lymph tubes and nodes are scattered all through 
the body, but are especially numerous in certain places. 

8. Where are nodes shown in Fig. 29 ? 




Fig. 29. Some lymphatics of the head, neck and axilla (arm 
pit), lying just beneath the skin. Note the point to which all the 
lymph tubes converge, where the lymph is poured into the vein. 

Veins. Place your left hand on a piece of paper 
and trace its outline with a pencil. Sketch in this 
outline the veins you can see in the back of the 
wrist, hand and fingers. If you tie a bandage 
around your arm the veins will stand out more 
clearly. If your own hand is so plump that you can- 



CIRCULATION 



93 



not see the veins clearly, sketch from the wrinkled 
hand of an elderly person. With a bandage or with 
your right hand, compress the left wrist; slowly and 
carefully slip the compression down toward the 
hand. The veins seem unusually swollen on the 
proximal (near) side of a valve. Note their ap- 
pearance on the distal (far) side. In your sketch 
mark the locations of all the valves you can find. 

1. Are the veins in the back of your hand arranged 
like the tributaries of a river, the smaller separate from 
each other and flowing into the larger, or are they con- 
nected by frequent cross veins? 

2. What advantage is there in their arrangement? 
They are said to anastomose. 

3. All the blood vessels which you see through the 
skin are veins. There is also a set of veins lying deep 
in the arm. What is the advantage of two sets? 

4. Why have the arteries the deep position only? 
Figure 30 shows diagrammatically the principal ar- 
teries of the arm and hand. 

1. If the circulation through the radial artery were 
stopped, how would the hand receive the blood supply? 

2. Trace the course by which the blood would get to 
a branch about the middle of the ulnar artery, if the 
ulnar were closed near its proximal end ? 

3. Is each finger supplied by one or by two branches 
from the palmar arch ? 

4. Do the veins [Fig. 31] of the arm have more or 
fewer anastomosing branches than the arteries ? 

5. Why is this desirable? 

6. Why are there more large veins than arteries in the 
arm? 



UPPER 

ARM 

ARTERV 



Fig. 30. The 
chief arteries 
of the arm and 
hand. Each 
finger is sup- 
plied by two 
branches, as is 
represented in 
the first finger. 

Fig. 31. The 
principal super- 
ficial veins of 
the arm. The 
hand and three 
fingers are left 
blank. 

Fig. 32. Ar- 
teries just un- 
der the skin of 
the head. 




Pig. 31. 



Fig. 32. 



CIRCULATION 



95 



7. Figure 32 shows the superficial arteries of the head. 
Where does the main trunk lie? Put your linger over it 
in your head and neck and feel the pulse as many places 
as you can. 

8. Do the smaller arteries take a crooked or a straight 



9. Descrihe the location of the veins of the head and 
neck shown in Fig. 33. 



CXTEBSAL 
JUGULAR 




NTEftNAt 
JUGULAR 



Fig. 33. Some veins of the head and neck. 

10. Why should the large veins he located near large 
arter: 

11. Are anastomoses in the veins frequent or not? 

12. Hie general plan of the blood circulation is shown 
in the diagram. Fig. 34. Compare this with the less 
diagrammatic representation in Fig. 35. 

13. What vessel receive- the blood from the left ven- 
tricle and distributes it to the body? 



9 6 



PHYSIOLOGY AXD HYGIENE 



14. The first large branches to leave the aorta carry 
blood to what parts of the body? 

15. What is the name of the main artery continuing 
from the arch of the aorta and running downward, lying 

HEAD 



RIGHT 
AURICLE 

RIGHT 

VENTRICLE 



ASCENDING 

VENA CAVA -" ( 4r- 



LEFT 
* VENTRICLE 



PORTAL 




DOR6AL 
AORTA 



CAPILLARIES] 
OF STOMACH \„^ 
INTESTINES * N 
AND PANCREAS^ 



--«■> KIDNEY 



-LEG 



Fig. 34. Diagram of the blood circulation. Blood con- 
taining- much oxygen is scarlet, blood containing much carbon 
dioxide and little oxygen is dark red. In the lungs, liver, and 
kidneys the blood goes through sets of capillaries. 



CIRCULATION 



97 



anterior to the vertebral column ? Its very small branches, 
to the chest and elsewhere, are not indicated. 

1 6. Trace, by naming in order the vessels through 
which it goes, the course of the blood from the heart 
to the kidneys and back to the heart. 



FROM 

MIAO 




ASCENDING 
VENA CAVA 

TO STOMACH 

AND 

INTESTINES 



KIDNEY _ 



DESCENDING 
AORTA 



Fig. 35. The heart and chief blood vessels in the chest and 
abdomen. 

17. To what chamber of the heart is the blood 
returned ? 

18. From which chamber does the blood go through 
the pulmonary artery to the lungs? 



98 PHYSIOLOGY AND HYGIENE 

19. To which chamber does it return from the lungs? 

20. How many pulmonary veins enter the heart ? 

21. What organ receives blood from a vein as well as 
from an artery? The portal system is better shown in 
Fig. 36. 

22. From what organs do the branches of the portal 
vein collect blood ? 



LARGE 
INTESTINE 
OR COLON 



SMALL 
INTESTINE 



Fig. 36. The portal vein and its tributaries. The transverse 
colon, part of the duodenum, etc., are cut out. 

23. Trace from the heart and back to the heart the 
course of the blood that supplies the pancreas. 

24. Trace the course of the blood that supplies the left 
side of the head. 

25. Trace the course of the blood to the right arm and 
back. 

26. Starting from the left ventricle, trace the course of 
the blood to the leg and back again. 



CIRCULATION 99 

Why the blood circulates. Each contraction of 
the heart sends blood spurting through the arteries. 
This impulse of the blood causes the walls of the 
arteries to give or distend. When the heart mus- 
cles relax, the elastic artery walls spring back to 
their former diameter, pressing on the blood' and 
sending it forward in a continuous stream. The 
blood is forced into the capillaries, crowding that 
which is already there into the small veins. The 
blood in the small veins is pushed into the larger, 
ever crowding forward that which is ahead of it. 
Thus the chief power that makes the blood move 
from the heart through all the tubes and back to 
the heart is the heart muscles. 

There are, however, two accessory forces that 
we should notice. Every time a vein in any part 
of the body is compressed, either by the bending 
of a joint or by the contraction of a muscle, the 
blood is squeezed out of it and must move toward 
the heart, since the valves prevent a backward 
motion. When the compression is relaxed, blood 
flows into the vein again. Thus exercise quickens 
the circulation. Determine why the arteries are 
less affected by these compressions than are the 
veins. 

When we expand the chest in breathing, the 
pressure inside the chest is lowered, and blood from 
veins in the abdomen, and especially in the neck, 
is forced into the chest through the large veins 



100 PHYSIOLOGY AND HYGIENE 

leading to the heart. In exhalation the contraction 
of the chest cannot force the blood back through 
the veins, since the valves prevent. Thus respira- 
tion is a process of pumping the blood in the large 
veins into the chest. 

The lymph is forced through the lymph tubes in 
almost the same way that the blood is driven 
through the veins. In the tissue, the lymph is 
under slightly greater pressure than in the large 
tubes, hence is flows slowly toward the lower pres- 
sure. Every compressing movement squeezes the 
lymph tubes, and the valves direct the flow toward 
the heart. The main lymph trunk runs through the 
chest, and the lymph, as well as the blood, is 
pumped with every respiration. 

Rate of blood flow. The blood moves quickly in 
the large arteries and more slowly in the small, 
averaging about twelve inches per second. In the 
veins the blood moves more slowly, about eight 
inches per second on the average. In the capillaries 
the blood moves most slowly. It is there most 
spread out, that is, the aggregate capacity of the 
capillaries is greater than that of the arteries that 
supply them, or the veins into which they discharge. 
Of course the short circuits, for example to the 
head, are made in less time than the long circuits, 
such as to the hands and feet. 

The lymph flows more slowly and more irregu- 
larly than does the blood. A substance injected 



CIRCULATION 101 

into a lymph space has been found in the blood, 
having passed through the small lymph tubes-, the 

nodes, and trunks and nearly a complete blood cir- 
cuit, in a few minutes. 

I. If the blood weighs one-twelfth as much as the 
whole body, and if a ventricle holds about three ounces, 
and the heart makes eighty beats a minute, how long 
would it take to pump a quantity of blood equal to all of 
yours through your aorta ? 

Regulation of the amount of blood. It is very 
important that the amount of blood going to each 
part of the body be carefully regulated. Just after 
dinner a large quantity of blood is needed in the 
mach, and when the food has passed on to the 
intestine less blood is required in the stomach. 
W'ljcn we are studying diligently, much blood is 
needed in the brain, and when we are sleeping less 
blood is needed there. How the supply of blood 
i- controlled is the question before us now. 

If the heart beats more rapidly, more blood is 
sent through the arteries to all parts of the body. 
If the heart beat becomes slower less blood goes 
rywhere. The regulation of the supply to any 
organ must depend not upon changes in the heart 
beat, for that affect- the whole body, but rather 
upon directing to the particular organ a larger or 
aller portion of the current going through the 

neral arteries. This regulation is accomplished 
by chai n the diameter- of the arteries or the 



102 PHYSIOLOGY AND HYGIENE 

veins, or of both arteries and veins of the particular 
organ. When the circular muscles in the walls of 
an artery relax, the blood pressure distends the 
tubes. Since the enlarged tubes offer less resist- 
ance to the blood, a larger and more rapid stream 
flows through them. This larger stream presses 
more vigorously into the capillaries, distending 
them slightly and flowing more rapidly through 
them, and through the veins beyond. When the 
circular muscles in the walls of an artery contract, 
the diameter of the tube becomes less, the blood 
meets more resistance and flows through in dimin- 
ished quantity. 

The muscles in the walls of the veins and arteries 
are under the control of nerves (called vasomotor 
nerves) which cause them to contract or to relax 
just as the quantity of blood required is less or 
greater. The changes in the diameter of arteries, 
you observe, is not in the large trunk vessels, but 
in the smaller tubes which supply organs or parts 
of organs. 

The muscles of the walls of some small blood 
vessels lose their "tone," their power to contract 
and bring the tube to its normal size, so the tubes 
are distended with a slowly moving dark-colored 
blood and they become noticeable in the skin. Re- 
peated exposure to the weather, habitual excessive 
use of stimulants, or simply old age may produce 
such results. 



CIRCULA1 [ON 



103 



1. When you blush arc the arteries which supply the 
skin of the face enlarged or constricted? Are the mus- 
cles relaxed or contracted? 

2. When your throat is inflamed what change has oc- 
curred in the blood vessels of the mucous membrane? 

C. The Heart 

General plan. The function of the heart is to 
make the blood move in a continuous stream 
through the blood tubes. Its essential structure is 
a cavity or chamber, called a ventricle, surrounded 
by muscle. Blood is received into the open ven- 
tricle, then the muscle contracts and squeezes it 
out into the artery. Just above the ventricle is a 
small chamber called the auricle, through which 
the blood from the veins passes on its way to the 
ventricle. While the ventricle is contracting and 
cannot receive blood, the auricle expands and holds 
for half a second the blood coming from the veins, 
then passes it on into the opening ventricle. The 
heart is a double pump with two auricles and two 
ventricles. All the blood goes through a double 
circulation — to the lungs to get oxygen and to give 
off carbon dioxide and to the remainder of the body 
to distribute the oxygen and nutritive materials, 
and to collect the waste. 

The human heart i^> SO nearly like that of the 
ep and the pig that we may well Study the organ 
from one of these animals. If you get from the 
butcher the whole pluck (heart, liver and lung 



104 PHYSIOLOGY AND HYGIENE 

you will have the entire heart together with the 
largest arteries and veins adjacent. If you buy the 
heart only, the auricles and the tubes are usually 
trimmed away. Make a cut through the muscular 
wall of each chamber large enough to allow you to 
explore the interior thoroughly. 

STUDY OF A SHEEP'S HEART 

1. Find the four chambers of the heart. Which have 
thick walls ? Which have thin walls ? Why are they so ? 

2. How many veins enter the right auricle? Pass a 
seeker (a small, smooth, blunt-pointed rod) through each. 

3. With a seeker or with your finger explore the veins 
entering the left auricle. Where do they come from? 

4. Explore the artery leading out of the right ventricle. 
Where does it go? Describe the semi-lunar valve in it. 

5. Explore the artery leading from the left ventricle. 
Describe its position and its valve. 

6. How do the walls of the arteries differ from those 
of the veins? 

7. About how large is the opening between the right 
auricle and the right ventricle? Describe the tricuspid 
valve guarding it. To what are the lower ends of the 
valve threads (chordae tendinae) attached? What is 
the function of these cords? 

8. Point out the difference between the mitral valve 
(left side) and the tricuspid. 

9. Describe the inner surface of a ventricle; of an 
auricle. 

10. The pericardium, or sack enclosing the heart, is a 
serous membrane. [See Fig. 43.] If it is not altogether 
cut away, describe its surface. 

11. Make a diagram showing the chambers, valves, 



CIRCULATION 105 

veins and arteries of the heart, and by arrows indicate 
the eourse of the blood through them. 

Rate of heart beat. Whenever the heart con- 
traets the blood is forced into the arteries with 
such pressure as to distend these tubes perceptibly. 
They become harder and tend to straighten out. 
These changes can easily be felt by pressing the 
fingers gently over an artery that lies near the skin. 
This is feeling the pulse. 

t. Get the pulse in your wrist between the radius and 
the tendons. Count it for one minute. What is the rate 
of the heart beat? 

2. Exercise briskly for two or three minutes ; count the 
pulse again. What is the rate? Why need it be 
different. 

3. Let each pupil of the class report the rate of his 
heart heat while sitting still, and also after exercise: get 
the averages. They are probably somewhat higher than 
adult averages. A baby's heart beats 120 to 130 times 
a minute. 

Character of heart beats. The character as well 
a- the rate of the pulse is important. Most hearts 
do not beat with perfect regularity, even in health; 
and disease produces a variety of changes in both 

the rate and the character of the pulse. 

T. Get the pulse of your body in as many different 
places a- you can. Is it usually in an exposed or in a 
protected situation ? 

2. Are your pulse brat- steady like the tick of a clock, 
or do the intervals between beats differ? 

3. 1- there any difference in tin- strength of the brat-? 



106 PHYSIOLOGY AND HYGIENE 

Innervation. The beating of the heart, like all 
other activities of the body, is under the control of 
the nerve system. It seems probable that the heart 
muscle can contract without nerve stimulus, yet the 
rate and the strength of the heart beats are con- 
trolled by the nerve centers. Within the heart are 
a number of small ganglia from which nerves go to 
the muscles of the organ. (See Figure 22.) These 
local centers are controlled by nerves from the 
spinal cord, medulla and sympathetic ganglia. The 
nerve fibers from these various centers are rather 
complex. Some fibers of a strand carry currents 
which make the heart beat more rapidly, and other 
fibers carry currents which make it beat more 
slowly. A blow in the "pit of the stomach" may 
retard or even stop the heart beat. What large 
sympathetic center does it affect? (Page 75.) 

Nourishment of heart muscle. The heart muscle 
is nourished, not by the blood that it pumps, but 
by a small amount supplied by a special artery. 
The blood passes through the large chambers of 
the heart and in so doing does not get into the 
tissues of that organ. A small artery (coronary) 
branches from the aorta just behind the semi-lunar 
valve and sends distributaries throughout the heart 
muscle. The blood can flow into the muscle only 
when the muscle is relaxed, and every contraction 
squeezes the blood out of the capillaries and small 
veins and into the larger veins. Why does the 



CIRCULATION 



107 



coronary artery branch from the aorta behind the 
valve; that is, on the side away from the ventricle? 

Hygiene. A good circulation means a strong 
heart, elastic vessels, and the ability to change 
readily the quantity of blood circulating to any part 
of the body. Exercise is a prime necessity in main- 
taining a good circulation. It should usually be 
moderate, but occasionally extremely vigorous, 
that the heart and arteries may be trained for any 
requirement of the body. If one has a serious 
defect in the heart, violent exercise should be 
avoided, and the moderate exercise should be care- 
fully supervised by a competent physician. 

There is a progressive hardening of the vessels 
of old people. This accounts for their sudden fits 
of dizziness on rising or on unusual mental exer- 
tion. The arteries, having lost much of their elas- 
ticity, do not dilate promptly to meet the call for 
increased blood supply. The foremost cause of 
early arterial degeneration is alcohol. "A man is 
• Id as his arteries," and a drinker of alcohol is 
old before his time. The heart also suffers from 
alcoholism. Its muscles waste away and some 
fibers partly turn to fat. The organ, which is nor- 
mally firm, may become so flabby through alcoholic 
degeneration that, if held by its tip, it falls oVer 
like a rag. 



CHAPTER VII 
RESPIRATION 

We shall study in this chapter how the cell gets 
oxygen from the atmosphere and how the carbon 
dioxide produced in the body is carried away. The 
protoplasm of each cell performs an act of respira- 
tion in taking from the surrounding lymph the 
oxygen it needs and in transmitting to the lymph 
the carbon dioxide it produces. This is called 
internal respiration. The lymph gets oxygen from 
the blood and brings carbon dioxide back into the 
blood. 

Why the gases move, the oxygen from the blood 
to the cell and the carbon dioxide from the cell to 
the blood and lymph, may be briefly explained as 
follows : A gas always tends to distribute itself 
evenly through space. If there is more of it in one 
place than in another, some moves from the place 
where there is much to. the place where there is 
little. This movement can go on through liquids 
and moist membranes. Protoplasm uses up the 
oxygen brought to it, leaving very little in the cell. 
Therefore the oxygen passes from the blood, where 
it is in abundance, through the lymph to the cell. 
In the blood oxygen is held in chemical combina- 

108 



RESPIRATION 109 

tion in the reel corpuscle. As the oxygen in the 
plasma is given off, the red corpuscles undergo a 
chemical change, giving off oxygen to the sur- 
rounding plasma, and so keeping more oxygen in 
that fluid than in the lymph outside. Since carbon 
dioxide is produced by the activities of the proto- 
plasm, there is always more of it in the cell than 
there is in the lymph and blood. As long as the cell 
is active the carbon dioxide flows from the cell into 
the lymph and blood. 

In the lungs the blood containing much carbon 
dioxide is exposed to the air, which contains very 
little, and the carbon dioxide passes from the blood 
to the air. At the same time, the oxygen passes 
from the air in the lungs into the blood, because 
the red coloring matter in the corpuscle attracts it. 
It combines chemically with the red corpuscle, and 
can be held in large quantity. 

The principles involved in this problem will be 
clearer if we observe their comparatively simple 
operation in some of the lower animals. In small, 
soft-bodied water animals no special respiratory 
organ is necessary. The carbon dioxide goes from 
the cells of the animal directly into the water, and 
the oxygen of the air which is dissolved in the 
water is taken directly into the cells. In larger 
water animals the gases cannot readily pass be- 
en the surface and the inner cells, so there must 
be a fluid (blood) circulating from the interior cells 



110 PHYSIOLOGY AND HYGIENE 

to some place at the surface where the gases can 
be interchanged. This place is usually developed 
just for the purpose of respiration, and is especially 
adapted to that end. It is called a gill. The essen- 
tial structure of the gill is a thin membrane with 
the blood on one side and the air of the water on 
the other. Some of the oxygen from the water 
passes through the membrane into the blood, and 
some of the carbon dioxide passes out from the 
blood into the water. In animals which live in the 
air the respiratory apparatus cannot be a gill tuft 
outside the body; it would collapse and dry up. 
Instead, it is a set of tubes which bring the air into 
the body. In the insects the tubes run to all parts 
of the body and so distribute the air directly. In 
the vertebrates the air tubes are gathered into one 
place, the lungs, to which the blood is brought for 
the exchange of gases. 

Air passages. Study Figures 37 and 38. The 
pharynx is the chamber at the back of the nose and 
mouth, through which both food and air pass. Its 
walls are soft and loose, composed of muscle and 
covered with mucous membrane. In the lower part 
of the pharynx are the troublesome tonsils, which 
seem to be of no use, and are commonly taken out 
if they repeatedly become inflamed. In the upper 
part of the pharynx is located a similar organ, 
called the pharyngeal tonsil. It often becomes en- 
larged in children, obstructs the nasal passage and 



RESPIRATION 



III 



develops mouth-breathing. Catarrh usually fol- 
lows. The growths obstructing the nasal passage 

are called adenoids. Since the Eustachian tube 

from the middle ear opens into this region, adenoids 



C E -CBR*. M 



EUSTACH 
UBE 



CEPtBELLLM 




ESOPHAGUS 



Fig. 3~. Median section through the head and neck. 

may cause deafness. If the}- produce the symptoms 
mentioned, they should be removed. 

The pharynx is continuous below with the 

esophagus, and from it the air passes through the 

glottis into the larynx. The pharynx and glottis 

are open as we breath, but when we swallow the 

1 or water is pushed down the pharynx into the 



112 PHYSIOLOGY AND HYGIENE 

esophagus by the contraction of the muscular walls. 
This blocks the air passage. As the food comes 
into the pharynx from the mouth, the glottis is 



Fig. 38. Front view of the larynx L, trachea T, bronchial tubes 
B, bronchioles bt. 

closed by a lid called the epiglottis, which is folded 
backward, thus preventing the food's getting into 
the larynx. Sometimes a breath through the 



RESPIRATION 



113 



mouth may draw a particle of food or a drop of 

water into the larynx. The tender lining of this 
organ is irritated and a cough is reflexly set up to 
expel the intruding particle. 

1. Is the air passage straight or crooked? 

2. As the air moves through this passage, striking 
against the moist sides, what becomes of the dust and 
germs in it? 

3. By what structure is the surface lining of the nose 
cavity greatly increased? 

4. How is the temperature of the air entering the lungs 
affected in its passage through the nose? The air be- 
comes nearly saturated with vapor in the nasal passage, 
so that it will not dry up the lungs. 

5. Give three reasons why we should breath through 
the nose rather than through the mouth. 

The larynx. The larynx is an irregular chamber 
whose walls are stiffened by plates of cartilage. 
Idie two vocal cords are not like violin strings, 
hanging free between their fastenings, but they are 
narrow folds of mucous membrane fastened along 
their whole length to the larynx frame. They are 
on opposite sides of the larynx, leaving a narrow 
-lit between their edges. Small muscles change the 
size of this slit and the tenison of the cords, and 
thus regulate the pitch of the voice. 

i. Feel the larynx in the neck, the Adam's apple. How 
long i- it ? 1 low wide? 

J. When you -wallow what change occurs in the 
larynx? It i- this movement that closes the glottis. 



Il 4 PHYSIOLOGY AND HYGIENE 

For the study of the remainder of the air pas- 
sages, the trachea, and bronchial tubes, get a 
sheep's lungs from the butcher. 

Sheep lungs. Arrange the lungs in position, dis- 
tinguishing the right from the left. The ventral 
side has the deep division between the lobes, and 
the bronchial tubes branch into the dorsal part. 

i. What is the general color of the lungs? Is the color 
uniform ? 

2. Blow through a tube (a test tube with a hole in the 
bottom) inserted into the trachea, and inflate the lungs. 
How does the size of the inflated lungs compare with that 
of the collapsed lungs? 

3. Compress the collapsed lungs gently ; release the 
pressure. Is the lung tissue elastic or inelastic? 

4. When you stop inflating the lung, why does it col- 
lapse ? 

5. Put a lung or a piece of lung into water. Why does 
it float? 

6. On which side, dorsal or ventral, are the cartilage 
rings of the trachea incomplete? Compress the trachea 
gently and observe the movement. 

7. Compress the bronchial tubes gently ; are the rings 
complete or incomplete? 

8. Does this condition of rings prevent or make possi- 
ble a change in diameter of the air tubes? 

9. Describe the serous membrane covering the lungs. 
Is it smooth or rough ? Tough or tender ? 

10. Describe the mucous membrane that forms the 
inner surface of the trachea. Is it rough or smooth, dry 
or moist? Compare with the outside of the trachea. 

11. Do the veins and arteries leave and enter the lung 



RESPIRATION 1 15 

near the large bronchial tubes or at the outer margin of 

the lung' 

Mucous membranes. The cavities opening to 
the outside of the body are lined with mucous mem- 
brane. They may be thought of as infoldings of 

the skin. The lining cells of the mucous membrane 
are called epithelial cells. Sometimes, as in the 
stomach and intestine, they are in a single layer, 
like the cells of a honeycomb, and are fastened to 
a basement membrane. [See Fig. 3, D, also 39.] 
Sometimes, as in the mouth, they are flat and ar- 
ranged in layers lapping over each other like shin- 
gles. These two forms are called, respectively, 
columnar epithelium and pavement epithelium. 
The membrane is kept moist by a fluid, mucus, 
secreted by special cells. Some digestive fluids are 
also secreted by the mucous membrane, which, in 
places, is folded into glands to give more secreting 
surface. 

Serous membranes. Closed cavities of the body, 
such as the chest cavity and the abdominal cavity, 
are lined with a serous membrane. 'The cells of the 
serous membrane are flat and thin and its fibers 
abundant, making the membrane strong. Although. 
a serous membrane produces a little fluid to keep 
it moist, it is not an extensively secreting surface 
like the mucous membrane. Its function i^ to 
make smooth a surface thai moves on another so 
a- to prevent friction. 



n6 



PHYSIOLOGY AND HYGIENE 




Fig. 39. Section of mu- 
cous membrane of the tra- 
chea, magnified 350 times, 
showing cilia on the surface 
of the cells. 



The synovial cavity of the joint is a closed sack. 
It is, however, different from serous cavities, and 
forms a class by itself. 

Cilia. The mucous mem- 
brane of the trachea and 
bronchial tubes, of part of 
the larynx and part of the 
nasal cavity is covered 
with cilia, fine threads of 
protoplasm which project 
from the surface of the epithelial cell about 1/2000 
of an inch. The cilia move back and forth together 
very rapidly, making a wave movement like a field 
of wheat or oats in the wind. The waves progress 
toward the larynx, driving 
along the mucus and the dust 
and germs that have been 
caught in it. When the mucus 
reaches the larynx it produces 
an irritation which provokes a 
cough to expel it. If it were 
not for this cleaning device, the 
lungs would soon become 
clogged with the dust of the 
air we breathe. 

For how long a time after 
you have been in a very dusty atmosphere can you 
notice the black stain in the mucus from the 
throat? 




Fig. 40. Infundibu- 
lum, small divisions 
of the air spaces of 
the lung, magnified. 



RESPIRATION 



117 



Lobule. The smallest divisions of the bronchial 
tubes are about 1/50 of an inch in diameter. They 
end in sacks called lobules, or infundibula, which 
art partially divided into air chambers or vesicles, 
as shown in Figures 40 and 41. In the walls of 
the lobule are blood capillaries. [Figure 42.] The 
lining of the vesicles and capillary walls form the 




Fig. 41. Sectional view 

of the air sacks shown 

in Fig. 40. The black 

represent sections 

of blood vessels. 



Fig. 42. Capillaries, much magni- 
fied, which lace over the lining mem- 
brane shown in Fig. 41. 



thin membrane, found in all respiratory organs, 

through which the gases pass. 

Mechanism of breathing. Things we are con- 
scious of doing all the time, we are likely to think 
of as simple processes that need no explanation. 
When the question arises — What makes the air go 
into and out of the lungs? — we are inclined to 
answer, "We just 'breathe it in and out." But this 
i- no explanation. Watch your neighbor inhale and 
n< >tice your own inhalations. 

The result of these inhalation movements is to 



n8 



PHYSIOLOGY AND HYGIENE 



make the chest capacity greater. The air in the 
lungs, therefore, expands and is under less pres- 
sure. The greater atmospheric pressure without 
drives in more air. The muscles which cause the 
diaphragm to lower are in the diaphragm itself. 
The chest is moved upward and outward by mus- 



CAVITY OF PERICAROIUM 
STERNUM 



LEFT 
AURICLE 



RIGHT 
AURICLE 

AORTA 




PULMONARY 
VEINS 



BRONCHUS 



SYMPATHETIC 
NERVE 



SPINAL 
CANAL 



Fig. 43. Cross section of the chest. 

cles running from rib to rib, and from the ribs to 
the shoulders. 

1. In what direction does the front of your chest move? 

2. Does the movement make the chest cavity larger or 
smaller ? 

3. The diaphragm is a sheet of muscle and tendon. If 
it contracts, does it rise or fall? See Fig. 44. Does this 
make the chest cavity larger or smaller? 



RESPIRATION 



IIQ 




4. In inhalation in what direction do you observe the 
front of the abdomen just below the breast bone to move? 

5. What motion of the diaphragm would force the ab- 
dominal walls outward? You infer that the diaphragm 
moves in what direction in inhalation? 

6. Swing your hands up slowly till 
they meet as high as you can reach. 
Mow does the elevation of the should- 
ers affect the chest ? 

7. Let your body represent your 
backbone, your forearms represent 
your ribs, and your clasped hands 
your sternum. Should your arms 
slant up, or down, or extend out hori- 
zontally ? 

8. Raise the arms slightly. Does 
the motion make the space between 
the hands and the body greater or 

9. How may the front of the chest 
be made to move forward in inhala- 
tion ? 

10. Study exhalation in yourself 
and in your neighbor. In what direc- 
tion does the front of the chest move? 

11. Does this make the chest cav- 
ity larger or smaller? 

12. In what direction does the upper front part of the 
abdomen move? 

13. How does this affect the diaphragm? Does if 
make the chest cavity larger or smaller? 

14. The diminution of the chest cavity increases the 
pressure of the air in it, till the interior pressure is 
greater than the atmospheric pressure, and some of the 



Fi G. 44. D i a- 
grammatic repre- 
sentation of the 
trunk, to show the 
changes that occur 
in the diaphragm 
and front wall dur 
ing respiration. 
The dotted line 
shows the position 
at the end of in- 
halation. 



120 PHYSIOLOGY AND HYGIENE 

air is forced out. Is the greater muscular force ordinarily 
used in inhalation or exhalation? 

15. Expel the breath quickly but forcibly; where do 
you feel the muscles contract ? 

16. Explain how this muscular contraction can diminish 
the chest cavity. 

In ordinary respiration the elasticity of the lungs 
and of the walls of the chest is sufficient to cause 
the expulsion of the respired air; in forced respira- 
tion the ribs are pulled down and are swung inward 
partly by muscles in the abdomen and partly by 
muscles slanting down and back to the spine. 
You have already observed that when the walls of 
the abdomen contract the diaphragm is forced 
up. 

The products of respiration. The air that enters 
the lungs is the common atmosphere, — about 79% 
nitrogen and argon, 21% oxygen, .03% carbon 
dioxide, and a variable amount of water and dust. 
The air exhaled contains about the same quantity 
of nitrogen, but much less oxygen (16%), about 
one hundred times as much carbon dioxide 
(4.38%), scarcely any dust and much water vapor. 
The exhaled air contains also some substances so 
intangible that their nature cannot be determined. 
They seem poisonous, and give to the ill-ventilated 
room its bad odor. These, or similar substances, 
seem to be given off by the skin also. There is no 
benefit in the exhalation of water vapor, but it is 



RESPIRATION 121 

impossible to expose a mucous membrane and 
warm, moist blood to dry air without its evaporat- 
ing considerably. 

Ventilation. We could breathe in air containing 
less oxygen than there is in the atmosphere and an 
amount of oxygen larger than the normal is not 
harmful. The red corpuscles can take only a cer- 
tain quantity, and when they are satisfied the 
remainder of the oxygen is simply exhaled. We 
can exhale into an air having several hundred times 
as much carbon dioxide as there is in the atmos- 
phere, but much increase of carbon dioxide in a 
room means impure air. 

Experiments have recently been made to learn 
just why an ill-ventilated room is oppressive. We 
know that a "close" room makes one restless and 
unable to work at his best. One becomes sleepy 
and stupid and may even faint. It is not now gen- 
erally thought that there is too little oxygen or 
too much carbon dioxide in the room. But there 
is considerable support to the theory that the harm- 
fulness of bad air is due to substances given off by 
the skin and lungs, which cause the disagreeable 
odor of foul air. The most recent studies show 
very clearly that most of the discomfort of bad air 
i^ the result of its too high temperature and its 
faulty humidity. Bad air, when set in motion by 
an electric fan, may lose its oppressiveness. This 
ms to mean that when the perspiration is evap 



122 PHYSIOLOGY AXD HYGIENE 

orated and the skin cooled we do not suffer from 
poor ventilation. 

Much still remains to be learned about ventila- 
tion and the most desirable temperature and 
moisture conditions; but we can be sure of the 
desirability of (a) a circulating in preference to a 
stagnant air, (b) enough moisture to prevent the 
discomfort of drying the mucous membrane of the 
nose and mouth, yet not so much as to retard the 
evaporation of perspiration, (c) a temperature not 
above 70 degrees for ordinary rooms. There is 
indeed considerable reason for thinking that a 
lower temperature, between 65 and 68, and possibly 
less than 60, is preferable to 70 degrees. 

Count the number of inhalations you make in a 
minute, or better, since our own breathing is influ- 
enced by our thinking about it, study the respira- 
tion of your neighbor who does not know he is 
observed. 

1. How many inhalations are there a minute? 

2. If they are not all alike explain how some differ 
from others. 

3. Count the respirations of one who has just paused 
in vigorous exercise. How does the number compare 
with the previous count? 

4. The lungs take in at an average breath 30 cubic 
inches. At that rate, how many cubic feet would you 
need in a day if you were sitting still? 

5. That would fill a room of what dimensions? 



RESPIRATION u 3 

This does not mean that you could live all clay in 
a room of that size without ventilation. In a short 
time the harmful exhalations would make the air 
unfit for breathing, even before the oxygen was 
much depleted. If the exhalations could be carried 
off instead of mixed with the air of the room, the 
roomful of air would be sufficient for the day. But 
since we exhale into the air of a room, we need a 
much larger volume of air. A room should have 
from 800 to 1,000 cubic feet of space for each per- 
son occupying it, and, according to some authori- 
ties, a room is considered well ventilated only when 
there is brought in for each person 2,000 cubic feet 
of fresh air every hour. 

Impure air. The result of breathing impure air 
is often a headache and always dullness and de- 
creased vitality. This renders one more susceptible 
to contagious disease, especially to diseases of the 
respiratorv organs, such as colds, tuberculosis, and 
pneumonia. We do not commonly appreciate the 
fact that a cold i^ a contagious disease. It has been 
said that one should be ashamed of having a cold. 
implying that it results from careless exposure to 
drafts or neglect of wet feet or clothing. The cx- 
"ire docs cause congestion of the mucous mem- 
brane, but that is soon over if the disease germs 
do not establish themselves. We usually take cold 
by breathing the air of ill-ventilated rooms and 
cars, which i- loaded with million- of grerms from 



124 PHYSIOLOGY AND HYGIENE 

the crowded people. Polar explorers, subject to 
extreme exposure but in an atmosphere free from 
germs, do not have colds. We should avoid, as 
much as possible, not copious drafts of fresh cold 
air, but little, streams of cold air on parts of the 
body, wet feet and damp clothing, and more impor- 
tant than all, we should avoid the foul air of 
crowded rooms. 

Pneumonia (lung fever) and tuberculosis are 
commonly spread through lack of good ventilation. 

Besides the germ diseases there are other in- 
juries to the respiratory organs that come through 
impurities in the air. The dust is not all taken out 
of the air as it goes through the air tubes, and 
some of it is carried into the lobules, where there 
are no cilia to remove it. There it may accumulate 
till it interferes with the respiration and injures the 
delicate membrane on which it presses. The fine 
coal dust in the smoke of our large cities injures 
the lungs of all of us. The lungs of coal miners 
are black with the dust they breathe and are very 
susceptible to contagion. If the dust is gritty, com- 
posed of minute fragments of stone or metal, it is 
especially harmful. Stone cutters and metal grind- 
ers are short-lived, killed by the dust of their trades. 
A well-ventilated shop, bringing fresh air to the 
workmen and carrying away harmful dust, would 
make these trades less dangerous. One of the most 
harmful occupations is glass-blowing. The work- 



RESPIRATION 125 

man compresses the air in the lungs to such an 
extent as to injure the delicate membrane of the 
lobules. Glass-blowers can work at their trade but 
a few years and many die of lung disease. 

How to ventilate. In dwelling houses the 
amount of space to each person is so large that 
little attention is paid to ventilation. The air goes 
through porous walls and through the cracks about 
the windows and doors and thus makes it possible 
to live in comfort without special ventilation; but 
the house air is far inferior to the out-of-doors air. 
The most approved treatment of tuberculosis keeps 
the patients out of doors day and night. The fresh 
air that works their cure is best for well people also. 
In crowded tenements the air is usually laden with 
disease germs and other harmful substances and is 
deficient in oxygen. Occupants of such buildings, 
the great mass of the city's poor, have almost uni- 
versally a low vitality and are, therefore, in large 
numbers the prey of lung diseases. 

Most of us depend on opening the windows for 
ventilation. In summer when the windows can be 
kept wide open, this does very well for rooms that 
are not crowded. In winter when the outside air 
IS cold we seldom open the windows wide enough 
to get adequate ventilation. A small opening at 
the top and another at the bottom produces a good 
circulation of air, the cold, heavy air coming in 
below and driving out the warm, lighter air above. 



126 PHYSIOLOGY AND HYGIENE 

But this produces such a cold draft that it is objec- 
tionable. The difficulty may to some extent be 
avoided by a board placed on the window sill, slant- 
ing inward and upward so as to give an upward 
direction to the incoming cold current. The fresh 
air then gradually settles through the room. The 
best arrangement is to pass the fresh air over the 
heating apparatus, so that it will come into the 
room properly warmed. Provision must be made, 
also, for the removal of the foul air. If its exit is 
near the floor, the cooler air will be taken out, and 
the heating will be more economical. The greater 
w r eight of the cold air coming in is sometimes suffi- 
cient to produce a circulation, especially if the exit 
flue runs up to the roof beside the warm chimney. 
In large buildings, where the air must be distrib- 
uted to many rooms through long horizontal pipes, 
it is usually necessary to employ a fan to drive it 
through the supply pipes. 

Fresh air. There is one fad that never does any 
harm and in countless instances does incalculable 
good — the fresh air fad. To those in health fresh 
air brings red cheeks, bright eyes and vigor of 
mind and muscle. To the sick it sometimes brings 
health and happiness. The most approved treat- 
ment of pneumonia includes fresh air, even in win- 
ter when the air is bitterly cold. Tuberculous 
patients are kept out of doors as much as possible. 
They eat, read and sleep in the fresh air. Living 



RESPIRATION 127 

out of doors in cold weather implies warm clothing, 
so that the body is comfortable. However much 
our occupation compels us to work in a room 
whose ventilation is poor, there is no excuse for 
our sleeping in a close atmosphere. The best plan 
is to sleep on a porch or under a tent, with the 
fresh air circulating around us. If this is not con- 
venient, we can close our room door in winter to 
avoid cooling off the remainder of the house, put 
on sufficient blankets to keep us warm, and open 
the windows to let in the fresh air, — not an inch at 
top and bottom, but wide open so that the air may 
circulate freely around us. 

In some schools the children who are tubercu- 
lous, and those who have a low vitality, are put in 
fresh air rooms with the windows open. In cold 
weather suitable clothing keeps them warm. These 
children usually show a wonderful improvement in 
health as well as marked progress in their studies. 
Fresh air rooms for children in health seems 
equally successful. The pupils do better work and 
are almost altogether free from the colds which 
afflict pupils in other rooms. 

1. Explain the method by which your school room is 
heated and ventilated. 

2. Is there any special ventilating arrangement in your 

house? If so explain it. 

Drugs. Several stimulants and narcotics have a 
marked temporary effect on the respiration. In 



128 PHYSIOLOGY AND HYGIENE 

general, stimulants increase the rate of respiration, 
while narcotics diminish it, though there are excep- 
tions to this. The habitual use of drugs produces 
serious injury to the respiratory organs. People 
addicted to the use of alcohol are more subject to 
pneumonia and asthma than are others, while 
smoking injures the mucous membrane of the 
mouth, nose and throat. A cancer of the tongue 
not infrequently results from smoking a pipe. 



CHAPTER VIII 

FOODS 

Our need of food. We need food for two pur- 
poses: First for growth, and second for the repair 

of tissues worn in doing work and producing heat. 
For the first purpose, foods must supply the ele- 
ments which are in protoplasm, and foods used for 
the second purpose must contain a large amount of 
carbon, since most of the energy of the body is 
produced by the oxidation of carbon. It is not suf- 
ficient that the food simply contain the necessary 
elements, but the elements must be in such com- 
bination that the protoplasm can build them into 
its own structure. From the soil, plants take water 
(H 2 0), nitrates (KN0 3 ), potash salts (KC1), etc., 
and from the air, carbon dioxide (CO.). They 
combine these substances into protoplasm. (Do 
these raw materials contain all the chief elements 
of protoplasm?) Animals cannot do this. They 
must take their food from plants or from other 
animals in the form, or almost the form, in which 
it enters into chemical combination in their pro- 
toplasm. Our food, then, is composed of elabo- 
rated compounds obtained from other animals or 
from plants. There arc three classes of foods. 

129 



130 PHYSIOLOGY AND HYGIENE 

Nitrogenous foods. The element nitrogen is 
present only in certain food substances. They are 
called nitrogenous foods. All protoplasm of plants 
and animals, when it dies and is used for food, is 
included in this class; and since every piece of the 
plant or animal (except dead parts like old wood, 
hair, etc.) contains some protoplasm, we get more 
or less nitrogenous food in all we eat. Besides pro- 
toplasm there are a number of other nitrogenous 
food substances in both plants and animals, such as 
gelatin or the gluten in wheat. Our most common 
nitrogenous foods are all kinds of meat, except fat, 
the curds of milk, cheese, eggs, gelatin; among the 
vegetables, peas, beans and lentils; and all kinds of 
cereals except rice. 

Carbohydrates. Carbohydrates are composed of 
only three elements, carbon, hydrogen and oxygen. 
Common sugar is expressed by the formula 
C 12 H 22 O n , grape sugar by C G H 12 6 , and starch 
by n (C 6 H 10 O 5 ). The "n" means that the starch 
molecule is not just the 21 atoms indicated, but a 
certain number, perhaps 20 or more, times the 21 
atoms. Notice the amount of hydrogen compared 
with that of oxygen in the carbohydrates. Sugars 
and starches are the chief carbohydrate foods. 
Most of the sugar we use comes from the root, 
stem or fruit of plants. Milk is about 3% sugar. 

1. Name a root that supplies a large per cent of the 
world's sugar. 



FOODS 



131 



2. Name two plants whose steins supply sugar for our 
markets. 

3. What commercial sugar comes from a fruit or seed? 

Starch is the main food of the human race. It 
comes from nearly all parts of plants: wheat, corn 
and rice are seeds; sago is from a stem; potatoes 
are underground stems; sweet potatoes are roots. 
Figure 45 shows the ar- 
rangement of starch and 
proteid (nitrogenous ma- 
terial ) in beans and pota- 
toes. In many plant cells 
the only nitrogenous mat- 
ter is a small amount of 
protoplasm, nearly all the 
cell contents being starch. 
In peas, beans and lentils, 
however, most of the 
nitrogenous matter is not 
protoplasm, but a stored 
proteid, and composes 
about one- fourth of the 
whole seed. The vege- 
table cell wall is woody 
material (cellulose) al- 
most like starch. Some 
animals can use it for 
1. but in the human 
body it seems to be indigestible. The cellulose serves 





Fir,. 45. a — Cells of the po- 
tato, filled with starch, b— cells 
of the bean, Tilled with large 
starch grains and small proteid 
grains. 



132 PHYSIOLOGY AND HYGIENE 

a useful purpose, however, in giving bulk to the food. 
Fats and oils. Like carbohydrates, fats and oils 
are composed only of carbon, hydrogen and oxy- 
gen. They vary more in the ratios of the elements, 
and have a lower percentage of oxygen than do the 
carbohydrates. 

i. Name as many animal fats as you can that are used 
for food. 

2. Name as many vegetable oils as you can that are so 
used. 

3. At the usual atmospheric temperatures are the com- 
mon animal fats solid or liquid? 

4. In which condition are the vegetable oils? 

Using the following methods, test as many as 
you can of the food substances that come into the 
kitchen, to find out what kinds of food each 
contains : 

A. In a test tube containing a small quantity of 
strong nitric acid boil a bit of food for a few seconds. 
Be very careful not to get the acid on your hands or 
clothes. Drain off the acid and add enough ammonia to 
the food to neutralize it. If nitrogenous material is 
present it turns orange color. 

B. Add enough iodine crystals to a water solution of 
potassium iodid to give it a light brown color. Put a drop 
of this solution on some starch and observe the color you 
get. Find out whether raw starch or boiled gives the 
brighter color. 

C. Haynes' solution is used in testing for sugar. To 
make it, completely dissolve 30 grains of pure copper 
sulphate in y 2 an ounce of pure water (warm a little if 



FOODS 133 

necessary), mix thoroughly with ). 2 ounce of pure glyc- 
erine, add 5 ounces of liquor potassae (5% solution of 
KOH). In a test tube boil a little of this solution into 
which you have dropped a bit of the food to be tested. 
Try first some pieces of raisin or other sugary fruit. The 
red color you get is caused by the grape sugar. Boil a 
solution of cane sugar in 1/10 its volume of strong sul- 
phuric acid before testing; this changes it to grape sugar. 

D. Put on a piece of paper, such as filter paper, a tiny 
drop of oil and in another place a drop of water, and 
observe the characteristic translucent mark oil makes. 
Then rub on the paper a bit of food to see if it contains 
fat or oil. 

Test a piece of cabbage, of turnip, of bread, of meat, 
of egg — as many things as you can — by each of these 
four methods, and list the kinds of food found in each. 
The following is a convenient form for making your 
record : ■ 

Food Constituents 

Food 
Substance Nitrogenous Sugar Starch Fat 



Milk, Found Found Xot Found 

etc. found 

Sometimes you will be able to write not simply 
"found" or "not found," but whether the quantity 
is much or little. 

Inorganic foods. There are in the body certain 
salts not included in the classes of food given 
above. Most of them are taken incidentally with 
the various foods and with the drinking water. 
Only one, common salt, do we add to our diet inten- 
tionally. In ordinary drinking water we get much 



134 



PHYSIOLOGY AND HYGIENE 



more calcite (lime salt) than we need, sometimes 
more than is good for us. Potash is in most vege- 
tables. Lean meat contains about all the salts we 
need. 

Energy foods. Though energy is liberated by 
the oxidation of any food, the fats and carbo- 
hydrates are especially suited to supply energy, 
and are therefore often called the energy foods. 
While all foods are perhaps changed into the pro- 
toplasm in preparation for its down-breaking in 
the liberation of energy, the nitrogenous foods 
alone can supply all that is needed for the repair 
and growth of protoplasm. They are therefore 
called the food for growth and strength. 

Composition, Energy Value and Cost of Foods 



3 5 2 

Food, as purchased. a> i* 2 d 

Beef loin 13 52 16 17 

Veal, leg cut 3 68 20 7 

Mutton loin 16 42 13 28 

Pork loin 20 42 13 24 

Salt pork 82 86 

Tomato soup ...... 90 2 1 

Fowl 26 47 14 12 

Halibut steak... 18 62 15 4 

Oysters (solid). . . 88 6 1 

Eggs (hens')--., n 65 13 9 

Butter 11 1 85 

Whole milk 87 3 4 

Cheese (cream). .. 34 26 34 



73 
>> 

A 



& 

eg 

O 


CO 

< 
•9 

1.0 

•7 
.8 

3-9 


w 

* a 

C V 

1,025 

695 

1,415 

1,245 

3,555 


C 3 
cy 
ft 


0) 

05 C 


6 


1.5 
7 
•9 


185 
765 
475 


— 




3 


1.1 

•9 
3-0 


225 

635 
3,4io 






5 
2 


•7 
3-8 


310 
1,885 


.... 





FOODS 135 

Composition, Energy Value and Cost of Foods — Continued 



2 1 il s 

>» ■ O 9 03 c 

5 o "Z g TIm «m t L 

2 *j -> • & • co> o<^ On 

Food, as purchased, t ." g £ a € rt a u a rt C 

Wheat flour 12 11 1 75 .5 1,635 

Corn meal \2 g 2 75 1.0 1,635 

Oats (brTefast). .. 8 17 7 66 2.1 1,800 

Rice [2 8 .3 79 .4 1,620 

White bread 35 9 1 53 1.1 1,200 

Sugar 100 ... 1,750 

Beans (dry ) 13 22 2 60 3.5 1,520 

Beans (string).. 7 83 2 .3 7 .7 170 

Cabbage 15 78 1 .2 5 .9 115 

Onions 10 79 1 .3 9 .5 190 

Potatoes 20 63 2 .1 15 .8 295 

Sweet potatoes.. 20 55 1 .6 22 .9 440 

Tomatoes 94 .9 .4 4 .5 100 

Apples 25 63 .3 .3 11 .3 100 

Bananas 35 49 .8 .4 14 .6 260 

Grapes 25 58 1 1 14 .4 295 

Strawberries .... 5 86 .9 .6 7 .6 150 

Raisins 10 13 2 3 68 3.1 1,265 

Peanuts 24 7 19 29 18 1.5 1,775 

Walnuts ( Eng. ) . 58 1 7 27 7-6 1,250 

Chocolate 6 13 49 30 2.2 2,625 

The amount of energy yielded by oxidizing a 
pound of food is expressed in the heat units (cal- 
ories) column. The carbohydrate column is mostly 
starch, but is altogether sugar in milk and in small 
part sugar in most of the foods given. The data 
of this table is given somewhat differently by dif- 
ferent authorities. The figures here given are on 
the authority of United States Department of 
Agriculture. 



136 PHYSIOLOGY AND HYGIENE 

Fill in the cents per pound column with the 
prices of your markets (eggs \]/ 2 pounds per dozen, 
apples 12 pounds to the peck, potatoes 15 pounds 
to the peck, three or four bananas to the pound). 
Then reckon from that and the heat units column 
the amount of energy yielded by a cent's worth of 
each kind of food. 

1. In which food do you buy the most energy for a 
cent? 

2. In which food do you buy least ? 

3. What do you think is the reason that starch is man's 
chief food? 

4. Which kind of food yields the largest amount of 
energy per pound ? 

5. Which food yields least energy per pound? 

6. Why do people in very cold climates eat so much 
fat? 

The use of a food as an energy supplier depends 
upon its digestibility and upon the character of the 
waste substances that result from its oxidation. 
The carbohydrates are easily digested, and they 
oxidize to water and carbon dioxide. The carbon 
dioxide is easily removed from the body through 
the lungs, and the water is useful in the body. The 
wastes from the oxidation of nitrogenous foods are 
more complex and much more difficult to remove. 
Therefore, from both financial and physiological 
considerations, the fat and carbohydrate foods are 
the most economical sources of energy. We must 
not, however, choose our food altogether accord- 



FOODS 137 

ing to its energy value. It is well for us to take 

enough fat and carbohydrate food to supply the 
energy required for heating the body and for doing 

our work. But we must have nitrogenous food 
sufficient for growth and for the repair of the body. 

1. Ignoring the water, what food in the table shows 
a per cent of nitrogenous material large in comparison 
with the other constituents? 

2. From what foods would a vegetarian get his nitro- 
gen supply? 

Quantity. How much food of each kind one 
needs in a day depends so much on the age, size 
and activity of a person that no amount can be 
given that will just meet the requirements of even 
a majority of people. Each one must find out by 
experiment what he needs. The appetite is not an 
altogether reliable guide, because it is largely a 
thing of habit, and it is satisfied with quantity 
rather than quality. If we eat less than the custo- 
mary amount, though we may have taken sufficient 
for the needs of the body, the appetite calls for 
more. Growing boys and girls, living much in- 
rs, often Celt too little; other- too much. 

if the body is to lose nothing of its weight and 
from it- possibilities for work, it must receive as 
much energy in it- food as it uses up in it- work. 
In some experiments the quantity of work done in 

a day has been expressed in units of energy, so that 

the amount of food-energy needed is known. I>ut 



138 PHYSIOLOGY AND HYGIENE 

such special experiments are of slight value to peo- 
ple engaged in the varied pursuits of common life, 
and how much of the food should be nitrogenous 
and how much fat or carbohydrate is not so easily 
determined. An ideal ratio is given by one physi- 
ologist as 18 per cent nitrogenous, 8 per cent fat 
and 74 per cent carbohydrate. If one has difficulty 
in digesting fat he should decrease the amount of 
fat and increase correspondingly the amount of 
carbohydrate. 

Variety. A strong, healthy person does not need 
to pick and choose his food; he can thrive on any of 
the foods commonly used by man. If the quantity 
and quality do not depart too far from the ideal 
standard, he will get along very well. Of course, 
he cannot work and keep strong on a deficient 
diet, and a monotonous diet is likely to be deficient 
in certain things and to contain too much of others. 
Therefore, a varied bill of fare is more likely to 
give a better balanced ratio. If there is plenty of 
nitrogenous material and plenty of fat and carbo- 
hydrate, the body can take what it needs of each 
and let the superfluity alone, or from the excess 
fat can be produced and stored. Variety appeals 
to the taste, also, and it is always desirable to stim- 
ulate digestion by enjoying the taste of food. We 
can live on a wholly vegetable diet or on an exclu- 
sively meat diet, but a mixed diet is better bal- 
anced. Vegetarians, especially if they do not use 



FOODS 



139 



milk, eggs or cheese, need to exercise care in 
selecting foods containing salts and nitrogen — the 
most important constituents we get from flesh 
foods. 

1. From the table on page 134 choose the foods that 
have a high per cent of tissue-building (nitrogenous) sub- 
stance. 

2. If the water were eliminated from lean meat and 
peas how would they compare in the amount of proteid? 

3. What part of potatoes and cabbage would be pro- 
teid if the water were taken out? 

Condiments. Pepper, mustard and spices are 
often put into the food to make the taste more 
attractive. They are called condiments. In that 
they stimulate the digestive organs, they may be of 
use in the process of digestion. But most of the 
condiments irritate the mucous membrane, and, 
like other stimulants, if they are taken habitually 
and in considerable quantities, they lose much of 
their effect, and the organs do not work well with- 
out them. If used strong, the condiments dull the 
taste so that delicate flavors cannot be appreciated. 
Use them sparingly. 



CHAPTER JX 

STIMULANTS AND NARCOTICS 

A stimulant is something which increases the 
activity of the body or of a part of the body, and a 
narcotic is something which decreases the activity 
of the brain. By an increase in activity we mean 
that the chemical changes which occur in the cell, 
such as oxidation, are more rapid, and, conse- 
quently, the work done by the cell is greater. This 
requires more blood, which is supplied sometimes 
by an increase in the rate of the heart beat, some- 
times by a stronger contraction of the heart, some- 
times by enlargement of the blood vessels that 
supply the part stimulated, and sometimes by a 
combination of these methods. Alcohol, tea, cof- 
fee, nitro-glycerine, strychnine, belladonna, and 
many other drugs are stimulants. After the stimu- 
lating effects of some of these drugs, such as alco- 
hol and belladonna, are passed, a narcotic effect 
follows which may be profound if the dose is large. 
A man stupefied by liquor is in the narcotic stage. 
Some narcotic drugs, as opium and hash- 
eesh, have a noticeably stimulating effect at first. 
These complicated effects result in some confusion 
in classifying drugs, but if the stimulating effect is 

140 



STIMULANTS AXD NARCOTICS 141 

conspicuous, as in alcohol and coffee, the drug- is 
usually called a stimulant, while the term narcotic 
is given to those drugs whose chief effect is to 
retard action, as opium and tobacco. The confu- 
sion is made worse by the fact that one part of the 
body may be stimulated while another part is nar- 
cotized by the same drug. Cocaine, for example, 
deadens the local nerves of sensation while it stim- 
ulates the motor activities. Most stimulants and 
narcotics when taken in large doses are poison. In 
suitable dosage, however, they are valuable drugs; 
but they should be used only by those who under- 
stand their effects and will use them wisely. 

The harm in stimulants and narcotics comes 
from the habitual use of drugs that change the nor- 
mal physiological activities. The body seems to be 
elastic in its activities. By introducing some arti- 
ficial conditions you can force it out of its normal 
course of action, and when you remove your inter- 
ference, it springs back to its regular activities. 
But if the interruption is repeated frequently, espe- 
cially while the body is still immature, the elastic- 
ity is overstrained and the body does not perfectly 
recover its normal functions. Stimulating and nar- 
cotizing drugs are such intrusions upon the normal 
physiological activities of the body. Taken occa- 
sionally in very small quantities, they produce 
abnormal conditions from which the body seems 
t<> recover easily. They may then be used as medi- 



142 PHYSIOLOGY AND HYGIENE 

cines to meet occasional abnormal conditions of 
the body. But taken habitually, especially in con- 
siderable quantities, they produce lasting derange- 
ment of our functions. When the body becomes 
accustomed to a stimulant or narcotic, it fails to 
respond to a small quantity of the drug, so larger 
doses must be used. These quickly bring serious 
consequences. One accustomed to the use of a 
stimulant feels nervous and craves it, and is unable 
to work well when he lacks it. When he has a 
little he wants more and is not satisfied until he has 
taken a harmful quantity. Therefore, all stimulants 
and narcotics should be used with great care. The 
following paragraphs discuss several of the stimu- 
lants and narcotics commonly used. 

Tea. You know that tea is the leaf and tender 
shoot of a bush which grows in warm countries. 
Most of that which we use in America comes from 
China, Japan, or India, though the plants grow in 
other countries and can be cultivated in our own 
southern states. The leaves are not simply dried; 
they must be slightly fermented, then rolled and 
afterwards dried by heat (fired). This requires a 
good deal of attention, so the countries that have 
cheap labor trained to the work supply the world's 
market. The stimulating substance in the tea is 
called cafifein. It is dissolved out of the leaves by 
boiling water. There are also in the leaves other 
substances which are extracted by boiling. One of 



STIMULANTS AND NARCOTICS 



143 



these, tannin, lias a bitter taste. Tannin, obtained 
from the bark of trees, is used in making leather. 
Jf the tea leaves stand but a minute in boiling 
water, very little of the tannin is extraeted, but if 
the leaves are boiled or the hot water stands long 
on them, a decoction is produced which is harmful. 
Tea topers might almost be said to tan their stom- 
ach lining. Caffein, in the small doses taken in 
occasional cups of tea, is such a mild stimulant that 
no injurious effects are commonly noticed. But the 
excessive use of tea, especially if it is made strong, 
is to be deprecated. 

Coffee. Coffee is the seed of a pulpy fruit which 
grows on a small tree in tropical countries. Most 
of the world's supply comes from Brazil. The 
seed is cleaned from the pulp and then "cured," a 
process of fermentation and drying. The stimu- 
lating substance in coffee is practically the same as 
that in tea, caffein. Americans are more often 
intemperate in the use of coffee than in the use of 
tea, and are therefore more often injured by it. 
Also, it is commonly made much stronger than tea. 
The use of coffee by children is especially objec- 
tionable. Boys or girls who have become so accus- 
tomed to the effect of coffee in the morning as to 
feel the lack of it, ought to be aroused to the injury 
they are doing themselves in relying upon a stimu- 
lant instead of upon simple wholesome nourishing 

f< »<>d. 



144 PHYSIOLOGY AND HYGIENE 

Cocoa and chocolate. Much the same kind of 

stimulant (theobromine) as that in tea and coffee 

is found also in cocoa and chocolate, but in very 

small amount. Aside from the sugar and cream, 

there is very little food in a cup of tea and not 

much more in coffee, while cocoa and chocolate 

are nearly all food. The practice of preparing the 

chocolate and cocoa with a large quantity of milk 

and sugar makes them foods instead of stimulating 

drinks, and there is little danger of taking so much 

of them as to be injured. 

Alcoholic liquors. When we speak 

of stimulating drinks, we usually mean 

alcoholic liquors. Common alcohol is 

Fig. 46. produced by yeast growing in a solu- 
Yeast cells, . . . . . r™ 

highly mag- tion containing sugar. The sugar is 

are C biit Tittle chemically changed to carbon dioxide 

larger than an( j alcohol. A wood alcohol is manu- 
bactena. 

factured from cellulose, the woody 

part of plants. It is used for fuel, but never for 
medicinal purposes. It is a poison. The alcoholic 
liquors may be classed as follows: 

A. Simply fermented liquors. These are made 
by fermenting the extracted juices of fruits, as 
cider from apples and wine from grapes. The fresh 
juice contains no alcohol, but it does hold in solu- 
tion sugar and nitrogenous foods. The nitroge- 
nous substance is in part used up by the growing 
yeast, and the sugar is changed to carbon dioxide 




STIMULANTS AND NARCOTICS 145 

and alcohol. The liquor, thou, contains less food 
than did the fresh juice, but the alcoholic stimulant 

has been added. The fresh juices may be bottled 
boiling hot and so preserved without fermenting - . 
The simply fermented liquors contain from five to 
ten per cent of alcohol in the light wines, and up 
to 15 or 17 per cent in Madeira and Sherry. Such 
wines are "fortified" by the addition of alcohol. 
Champagne is heavily charged with carbon diox- 
ide, which makes it fizz. Koumis is fermented 
milk. 

B. The brewed liquors. Beer, ale and porter 
are brewed liquors. They are made from grains, 
mostly barley, instead of from sugary fruits. The 
grain is first malted. In this process it is soaked in 
water, then kept on a warm floor about three days 
till it has sprouted. In the sprouting of the seed, 
part of the starch is changed to sugar. The 
sprouted grain is quickly dried in a kiln, and is 
called malt. Malt is a rich food. In the process 
of digestion starch undergoes a change practically 
like that of malting. Malt, therefore, is partly 
digested starch together with a considerable 
amount of dried protoplasm and wood. In brew- 
ing, the malt is ground and boiled to extract the 
nourishing substances. Hops and various flavor- 
ing materials are put into the brew. The liquid is 
drawn off, cooled, stocked with yeasl and put into 
vats to ferment at a temperature of 38 to 40 



146 



PHYSIOLOGY AND HYGIENE 



degrees, — too cool for putrefactive bacteria to 
grow. The growing yeast does not consume all 
the food material in the malt; what remains makes 
beer a slightly nourishing drink. Yet the nourish- 
ment costs many times as much as would the same 
amount of energy in common foods, and its value 
is more than counterbalanced by the harmful 
effects of the alcohol. The alcohol in some beers 




Fig. 47. A still. A and B — retort, S — worm in T — cooling 
jacket, E — furnace, F — water for cooling jacket. 

is as low as two or three per cent, but in others is 
as high as six or seven per cent. 

C. Distilled liquors. Distilled liquors contain a 
large amount of alcohol, usually 35 to 50 per cent. 
The process of distillation is essentially as follows: 

Some alcoholic liquid, say wine, is put into a still, 
a tight metal vessel, and heated gently. The alco- 
hol evaporates much faster than the water in the 



STIMULANTS AXD NARCOTICS 147 

wine. The mixed vapors of alcohol and water are 
conducted through a coiled tube called the worm, 
which is kept cool by a water-jacket. The vapors 
going through the cool worm are condensed and 
trickle out of the still as a lienor containing much 
less water than was in the wine. This liquor may 
be redistilled as many times as desired, each time 
leaving in the still some of its water, and so becom- 
ing stronger. The distillate of wine is brandy or 
cognac. Rum is distilled from fermented molasses. 
Corn and rye are malted and fermented and after- 
ward distilled to make whiskey. The Japanese 
make sake from rice. A sort of whiskey is made 
from potatoes in northern Europe. Gin is whiskey 
in which juniper berries have been soaked. Substi- 
tutes for juniper berries are often used. 

D. The liqueurs. Various flavoring substances 
are mixed with dilute alcohol to make liqueurs. 
They are usually strong, often stronger than whis- 
key and brandy. Absinth is one of the liqueurs; 
it is made from wormwood, alcohol and water. 

The use of alcoholic liquors. The brewed liquors 
are used fresh, but wines and whiskeys improve 
with age. The last are not considered fit for 
medicinal purposes till they have been kept at least 
six or eight years in oak casks. Commercial alco- 
hol, 95 per cent pure, is made by several times 
redistilling the fluid obtained by malting and fer- 
menting corn and other grains. Or it may be 



148 PHYSIOLOGY AND HYGIENE 

made from potatoes or other starchy or sugary 
substances. It is a strong antiseptic and has many 
important uses in the arts. Wood alcohol is a rank- 
poison, but it is an economical substitute for com- 
mon alcohol for purposes such as burning, or for 
mixing shellac. 

Effects of alcohol. The physiological effects of 
alcohol differ with the quantity used. Alcohol is 
oxidized in the body and thus plays the part of food 
in supplying energy. But it does this no better 
than sugar and starch do; it costs many times as 
much, and it has a harmful drug effect in addition 
to its food function. Some'physicians think it val- 
uable as a food in certain diseases, but it is used 
much less than formerly, and for people in health 
it should never be used as a food. 

In general, the first effect of a small dose of alco- 
hol (for an average person, less than an ounce of 
whiskey) is stimulating. The heart beats become 
stronger and more rapid; the capillaries are dilated, 
especially in certain parts of the body, as the skin, 
the mucous membrane, and the brain. This makes 
thought and movement more sprightly. The nar- 
cotic after-effects of such a small dose are distinctly 
noticeable. When taken in larger quantities, the 
stimulating effects are more transient; that is, the 
conspicuous narcotic effects follow more promptly. 
The higher activities of the brain are the first to 
succumb to the narcosis; the judgment is impaired; 



STIMULANTS AND NARCOTICS 149 

the victim of the drug- talks nonsense, and does 
things of winch, in sober hours, he is ashamed. 
Then the muscular control is weakened; he is 
unsteady in walk. The senses also are dulled; the 
sight is confused; the pain of injuries is less acute. 
With the increase in the quantity of drug taken, 
narcosis becomes progressively more profound till 
it becomes a stupor in which nearly all the activi- 
ties are suspended. The respiration becomes 
labored, the heart-beat slow and irregular, and 
death ensues if the quantity of alcohol is sufficiently 
large. 

The effect of alcohol, taken in almost any ordi- 
nary quantity, is to gorge the small vessels of the 
skin with blood. If this is frequently repeated, the 
vessels become permanently enlarged, and the 
blood flows through them slowly, turning dark 
from its loss of oxygen. This accounts for the red 
and purple noses and cheeks of old topers. Other 
causes may produce similar effects in the appear- 
ance of the skin; the depressed circulation of 
elderly people usually shows in the skin of the face 

A small amount of alcohol stimulates the secre- 
tion of saliva and of gastric juice, and is therefore 
sometimes prescribed, usually in the form of bitter 
brewed liquors or light wines, as an aid to diges- 
tion. However, it loses its efficiency, as does any 
other stimulant, when u^ed habitually. In larger 
doses, the mucous membrane lining the stomach is 



150 PHYSIOLOGY AND HYGIENE 

seriously injured, and the digestive functions are 
otherwise impaired. 

You know that athletes in training do not use 
alcoholic drinks. They want their muscles to 
develop as fully as possible. This is best accom- 
plished with simple, nourishing food. Alcohol 
would interfere with the nutrition as well as with 
the contraction of the muscles. The interference 
of alcohol with the perfect nutrition of the body is 
most marked in the young, where the rate of 
growth depends so much on the quantity of food 
assimilated. Experiments with animals show that 
those given alcohol with their food do not grow so 
rapidly nor so large as those given nourishing food 
only. The practice of letting children sip from 
their parents' beer or wine glass cannot be too 
strongly condemned. 

It is often said that the beer used by the Ger- 
mans is a harmless, even beneficial, drink. True, it 
does contain nourishing substances and only a 
small per cent of alcohol; and there seems to be in 
Germany less intoxication than in America. But 
the beer users suffer heavily from their drinking. 
The quantity of beer used is often enormous; the 
body is overloaded with water, to get rid of which 
the kidneys are overworked and almost always 
become diseased. Then the constant irritation of 
small quantities of alcohol produces degeneration 
of the liver. The abdomen becomes distended, and 



STIMULANTS AND NARCOTICS 151 

dropsy is of frequent occurrence. Not the least of 
the evils of beer-drinking is over-nourishment. 
In general beer drinkers are likely to become far 
too fat, and, like fattened animals, they have little 
inclination to muscular activity and still less to 
mental activity. 

The excessive use of alcohol is responsible, more 
than that of any other drug, for serious derange- 
ments of various organs as well as the general 
breakdown of the whole body. The nervous sys- 
tem is the greatest sufferer. Weakness, tremor, 
morning headaches and disinclination to work 
without stimulants become habitual. Insanity is a 
frequent outcome. A slight shock or injury or a 
prolonged spree may end in delirium tremens, a 
state of continuous mental and muscular activity, 
which often terminates with heart failure and 
death. The nerve trunks may be affected, produc- 
ing terrible pain and even paralysis. The muscles 
become wasted under the influence of alcoholic 
excess. While the beer drinker is fat, the whiskey 
toper often becomes emaciated. His artery walls 
lose their elasticity. Breathing is difficult. The 
stomach becomes inflamed and its digestive power 
is seriously impaired, if not quite destroyed. You 
must not think that this whole list of ills is visited 
upon everyone who violates the laws of temper- 
ance, yet comparatively few people persist many 
years in the excessive use of alcoholic liquors with- 



152 



PHYSIOLOGY AND HYGIENE 



out falling a prey to some of these messengers of 
retribution. 

Opium. When dried, the milky juice that oozes 
out of scratches made in the green seed pod of the 
poppy becomes opium. Laudanum is a tincture 
(alcoholic extract) of opium, and morphine and 
codeine are white powders made from the, same 
drug. All these drugs have great value in medi- 
cine, and all have been woefully misused. They 
so thoroughly benumb the senses that they come 
as a great boon to those suffering prolonged pain. 
They bring such prompt and thorough relief that 
the sufferer is tempted to employ them again and 
again, till their use becomes a habit. The body 
becomes accustomed to the use of the drug, craves 
it, and is miserable when it is lacking. The opium 
drugs have at first a slightly stimulating effect 
which is quickly followed by a pleasant, and often 
blissful languor said to be filled with charming 
dreams. In large doses, the drug so depresses the 
vital activities that the heart-beat and respiration 
become very slow, and, in overdoses, they stop 
altogether. Under the habitual use of these drugs, 
the tissues of the body fail to assimilate sufficient 
nourishment, and rapidly waste away. The secre- 
tion of digestive juices is decreased, the blood is 
impoverished, the face is pale, the pupils dilate 
except when under the influence of the drug, head- 
ache, dizziness and tremor are frequent, the victim 



STIMULANTS AND NARCOTICS 153 

of the drug becomes a moral and physical wreck, 
and only by the most strenuous determination and 
careful treatment does he recover. The opium 
drugs are especially poisonous to children. Infants 
have been killed by doses so small as hardly to 
affect an adult. Some soothing syrups contain 
opium, and for this reason should be carefully 
avoided. The opium drugs should never be given 
except on a physician's order. 

There are other drugs valuable for their power 
to stimulate special organs or to deaden pain or 
bring sleep. Several of them are occasionally mis- 
used, as are alcohol and opium, to the pitiable ruin 
of their victim. Cocaine and chloral are of this 
number. AYe should remember that all these stim- 
ulants and narcotics are drugs, not food and drink, 
that they produce abnormal activities in the body. 
and that their legitimate function is to meet other 
abnormal conditions. The physician, the one who 
understands both the disease and the effect of the 
drug, is the only proper person to prescribe the 
medicine. Taken only occasionally and in very 
small doses, some of these drugs may produce no 
deleterious effects that can be noticed, but as they 
are used by those addicted to them, they are not 
simply harmful but ruinous. 

Tobacco. Tobacco is the leaf of an herb that 

\s in temperate and warm climates. It is used 

chiefly in three ways: for smoking, for chewing, 



154 PHYSIOLOGY AND HYGIENE 

and as snuff. Though it is often used pure, it is 
frequently mixed with substances which modify its 
flavor but have little physiological effect. The 
active drug in tobacco is called nicotine. It is a 
deadly poison. The reason the users of tobacco do 
not experience the poisonous effects of the drug 
more than they do, is because they get such 
exceedingly small quantities of it. Most of the 
nicotine is puffed out with the smoke. Smokers 
begin by using only small quantities of tobacco, 
and by the time they come to use it freely, their 
bodies have become accustomed to the drug. 

The body can become accustomed to almost any 
poison by taking small doses at first and gradually 
increasing them. In time a dose can be easity 
endured which at first would have been fatal. The 
poison that is tolerated by the body accustomed to 
it is by no means harmless. Though it does not 
produce the characteristic toxic effects, it injures 
the body in more subtle ways. Tobacco is one of 
such poisons. If taken the first time in consider- 
able quantity, it shows its poisonous nature ; vio- 
lent vomiting and headache ensue. Many people 
begin to use the drug so gradually that they never 
feel these toxic effects, and others seem to have a 
natural tolerance for the drug (as many people 
have for other poisons) so that the moderate quan- 
tity used never seems to affect them seriously. 
Nicotine, as used, is a mild narcotic. It dulls the 



STIMULANTS AND NARCOTICS 155 

sensibilities, renders nervous people somewhat 
easier in mind and inclined to languor. This dead- 
ening of the nerves brings its retribution in time. 
You may see on the streets and in the business 
houses of any city hundreds of men who are unable 
to hold their hands steady, because their nerves 
have been ruined by cigars. 

The heart is especially susceptible to the influ- 
ence of tobacco, as well as that of tea and alcohol. 
Young people are more likely to suffer from 
"tobacco heart" than are their elders. Boys are 
sometimes rejected from athletic contests and from 
occupations requiring a vigorous physique because 
their hearts show the evil effect of tobacco. If the 
heart of a boy is injured by smoking, it may, on the 
cessation of the evil practice, regain its normal 
activity; but sometimes it becomes permanently 
enlarged and weakened, even to a dangerous 
extent. It is impossible to say how many of the 
heart failures are due to the excessive use of 
tobacco. 

Headache powders. There are a number of 
drugs (antikamnia, orangine, bromo seltzer, etc.) 
much advertised and extensively used as cures for 
headache. Nearly all of them contain acetanalid, 
a strong heart depressant, a dangerous drug. Sin- 
gle doses have produced death. Taken frequently 
by people who often have headache, it produces 
characteristic disorders of the circulation. Head- 



156 PHYSIOLOGY AND HYGIENE 

ache is a result of faulty living. We should check 
it by improving our hygiene. Dosing with drugs is 
a poor expedient. If medicines are used, it should 
be only on the advice of a physician. 

The effects of all the stimulants and narcotics 
are too subtle to be fully stated in precise changes 
in the structure or function of any of the organs of 
the body. We see their effects partly in the bodily 
derangements and partly in the changes in the gen- 
eral moral tone of their victims — which is perhaps 
but the expression of more subtle bodily functions. 
We do not mean to say that a cup of tea, a glass of 
wine, or a cigar will impair the moral fiber of any- 
one, but it is a common thing to notice moral 
degeneration in those who habitually use stimu- 
lants and narcotics. The fine edge of courtesy is 
more than blunted in the man who complacently 
puffs cigar smoke into the atmosphere which his 
neighbor must breathe. Whether this moral dull- 
ness is a physiological effect of using the drug, or 
whether it is merely the failure to appreciate the 
iniquity of a customary thing, who can tell? The 
nastiness of chewing and snuffing has driven these 
practices from polite society, so we less often have 
occasion to observe their effects on the moral 
sensibilities of those who indulge in them. 

People addicted to the excessive use of alcohol 
and opium are pretty sure to show extreme moral 
degeneration in time. Their regard for truth and 



STIMULANTS AND NARCOTICS 157 

honor vanishes before their craving for the cus- 
tomary drug. Reduced to extremity, they feign 
sickness, lie, beg, steal, — do almost anything to get 
the means of satisfying their desire. The sure way 
never to he brought to this condition is never to 
use the drugs except on the prescription of a con- 
scientious physician. 

\Ye have tried in the preceding pages to show 
you something of the terrible results which come 
from the misuse of some common stimulants and 
narcotics. We should avoid these drugs because 
we justly fear their power for evil. But there are 
other reasons for abstaining from them. Consider 
the millions of dollars spent each year for tobacco, 
the hundreds of thousands of acres of the best land 
devoted to its growth, the thousands of men, boys 
and girls engaged in its manufacture (a very 
unhealthful occupation) — can we afford to waste 
much when there is such great need of money 
for necessities, of land for raising wholesome food, 
of workers to produce useful things? 

A still greater waste is the drink bill. A larger 
number of acres is given to raising the materials 
for its manufacture, a stronger army of laborer^ 
working to produce the liquors, and thousands 
more ruined by the beverage. We squander our 
materials, waste our energies and benumb our 
powers in that which harms but does not satisfy. 

And vet the world is full of great things to do. 



158 PHYSIOLOGY AND HYGIENE 

There are barren lands to clothe with forest and 
field, marshes to drain, canals to dig, works of art 
to make, magnificent cities to build, founded not on 
the bones of the weak and oppressed, but firmly 
grounded in equality and justice. This work can- 
not be done by people whose delight is in tickling 
their senses with drugs. It is a labor for strong 
men and women. We are summoned to mighty 
deeds. We must employ every resource we have, 
use every ounce of energy we possess, to respond 
to the call. We must go into training, as an athlete 
for a contest, nourish our bodies with the most 
wholesome food, discarding that which is harmful 
or questionable, and make us strong for the con- 
flict. The day of heroes is not past. Choose a 
worthy object for your life work, put yourself in 
training for it, and you will have nothing to fear 
from stimulants and narcotics. 



CHAPTER X 
DIGESTION 

At the beginning of this chapter we must con- 
sider the problem of what is accomplished by the 
digestive process, and why this action is necessary. 

We have seen that food is brought to the cell by 
the blood and lymph. There must then be some 
way in which the food can get into the blood. It 
cannot go through the skin, for that is too thick; 
so we have a digestive tract, a tube with verv thin 
walls extending through the body. But the w r alls 
of this tube are tight ; there are no openings for the 
passage of food. Liquids, however, can go through 
the pores of tight membranes. Therefore, the 
food, to get through the walls of the digestive 
tract, is brought to a liquid form. Digestion dis- 
solves or liquefies the food. Some foods, though 
liquid and capable of being taken into the body 
and carried about by the blood, are not in such 
chemical form that the protoplasm can assimilate 
them. Therefore, they must be changed into a 
form that is suitable for assimilation; and this 
work, also, is to a large extent clone in the digestive 
organs. Common sugar, for example, is soluble, 
but is changed in digestion into a different kind of 

159 



i6o 



PHYSIOLOGY AND HYGIENE 



sugar more acceptable to the protoplasm ; and 

milk, already a liquid, undergoes digestive changes 

before it goes into the blood. 

Digestive activities. The digestive activities are 

mechanical and chemical. Mechanically the food 

is chewed or rubbed into 
small fragments, and these 
are dissolved; or, if they 
cannot be dissolved, they 
undergo chemical changes 
till they are soluble. Such 
changes are accomplished 
by fluids called enzymes, 
which by their presence 
cause the foods to un- 
dergo certain fermentive 
changes. 

These changes break 
large molecules up into 
small molecules. For ex- 
ample, the glucose mole- 
cule is one-half the size of 
the cane sugar molecule 
from which it is derived, 

and perhaps one-twentieth as large as the starch 

molecule. 

The digestive tract. The long tube of irregular 

size passing from the mouth through the trunk is 

known as the digestive tract. Its considerable 




Fig. 48. The digestive 
tract. A — mouth, B — phar- 
ynx, C — esophagus, D — dia- 
phragm, E — stomach, F — 
small intestine, G and H — 
colon, I — rectum. Trans- 
verse colon is cut out. J — 
appendix. 



DIGESTION 161 

length gives large surface for the secretion of 
digestive juices and for the absorption of food. 
The greater part of the length, twenty feet or more, 
is the small intestine, irregularly looped in the 
middle of the abdomen. The large intestine, the 
last division of the tract, is about live feet long. 

i. Name the part of the digestive tract that connects 
the mouth with the stomach. 

2. The stomach lies in which side of the body? 

3. Locate the liver as compared with the stomach. 

4. Name in order the parts of the large intestine. 

5. Locate the appendix. 

6. Locate the pancreas. (See Fig. 52.) 

Mouth anatomy. The first digestive change 
occurs in the mouth. To study the anatomy of the 
mouth, face a good light and hold a small mirror 
so that you can get the reflection of the open 
mouth. The pharynx is a chamber common to 
the back part of the nose and mouth. Look as far 
back into the mouth as you can. Hanging down 
from the roof of the mouth, separating it from the 
pharynx, is the uvula. 

1. Describe the movement of the uvula as you gap. 

2. Feel with the tongue; what part of the roof of the 
mouth is bony? what part is soft? 

3. Describe the mucous membrane lining the mouth — 
it- feel, its color, its surface, etc. 

Chewing. The chewing of food divides it into 
small particle- so as to expose it more completely 



162 PHYSIOLOGY AND HYGIENE 

to the action of the digestive fluids. Vegetable foods 
need to be chewed more thoroughly than meat 
foods because the vegetable cell walls are woody 
and cannot be easily digested. Dense vegetable 
lumps swallowed without chewing are likely to 
remain lumps all the way through the digestive 
tract, and the contents of the cells are not digested 
out. The connective tissue and cell walls of meat, 
on the other hand, are digestible. A piece of meat 
in the stomach is reduced to minute fragments, and 
the digestive fluids get access to all parts of it. 
Most of us do not sufficiently appreciate the value 
of thoroughly chewing our food; or we are in too 
great a hurry, and chewing is necessarily a slow 
process. Those who make a habit of chewing their 
food well find that it tastes better, digests more 
easily and more thoroughly, and therefore less of 
it is needed. 

i. Does a lump of food have more or less surface than 
the particles to which it is reduced in chewing? 

2. Why is chewed food easier to swallow ? 

3. What animals chew their food much? 

4. What animals chew their food little? 

5. What kinds of food are used by animals of the first 
class ? 

6. What kinds by animals of the second class? 

The teeth. Study your teeth, using a mirror. 

1. How many are there in each jaw? 

2. According to the appearance of the crowns, divide 



DIGESTION 



l6 3 



the teeth into two classes. What arc the differences 
between the classes (a) in form, (J>) in function? 

3. Give the number in each class. 

4. When the jaws close, how do the back teeth meet? 

5. How do the front teeth meet 

6. Explain how the meeting suits the function. 

7. The dentist names the teeth on each side of each 
jaw, beginning in the middle, — central incisor, lateral 
incisor, cuspid, first bicuspid, second bicuspid, first molar, 
second molar, third molar. 

S. What is the meaning of each of these terms? 

9. Describe the crown of each kind. 

10. From extracted specimens describe 
the roots — number and shape — of as 
many as you can get. 

11. Put a tooth into a bottle of dilute 
hydrochloric acid. The bubbles you see 
are carbon dioxide, which is produced 
when hydrochloric acid comes in contact 
with limestone. We infer that the tooth 
contains a limestone substance. After 
the tooth has been in the acid for a day 
how has it changed? The material not 
destroyed by the acid is an animal sub- 
stance much like gristle. 

12. How does the substance of a tooth 
compare with the substance of a bone? 

13. Since the tooth is alive, all parts (except the 
enamel) must be supplied with food and oxygen. 

The dentine is similar to bone in having minute tubes 
through which the blood and small nerve fibers can pene- 
trate to all parts of it. Where do the blood vessels and 

nerves li< ee Fig. 49.) 

14. The gums cover wbat part of the- tOOth? 




Fig. 49. Sec- 
tion through 
a tooth. c — 
e n a 111 e 1, d — 
dentine. p — 
pulp cavity, g 
— gums, 1) — 
bone, c — ce- 
ment. 



1 64 PHYSIOLOGY AND HYGIENE 

Care of the teeth. The enamel of the teeth is 
the hardest substance in the body. It has neither 
pores, blood vessels nor nerves, but forms a com- 
pact surface to protect the softer parts of the 
tooth. Since it contains no protoplasm and has no 
blood supply, it cannot be repaired if it is injured. 
If it is cracked or worn through, there is exposed 
the porous, moist dentine in which germs rapidly 
produce decay. The enamel is sometimes injured 
by picking the teeth with pins and other hard .in- 
struments. A quill or wood pick or a thread is 
better. There is no better health investment than 
the care bestowed upon the teeth. 

Hot and cold drinks should be kept from the 
teeth as much as possible, because a sudden change 
of temperature is likely to crack the enamel. Bits 
of food allowed to remain between the teeth decay, 
producing an acid that destroys the enamel. Re- 
move them with a pick or thread after each meal. 
The teeth should also be brushed at least twice a 
day. The brush should have bristles of different 
lengths, that some may go between the teeth. If 
the brush is moved with a turning motion from the 
gums to the teeth, the bristles will not catch under 
the gums, rubbing them back and making them 
sore. A gritty powder will wear off the enamel, 
and therefore should be used but seldom ; a soft 
chalk or orris root is sufficient for the daily clean- 
ing. A mild antiseptic mouth wash, worked with 



DIGESTION 165 

closed lips back and forth between the teeth once 
a day, is beneficial. 

Have your teeth carefully inspected once or 
twice a year. Have cavities Idled as soon as they 
appear, before they get large. They give the 
breath a bad odor and harbor swarms of bacteria. 
The dentist scrapes out all the decay and germs and 
puts into the clean cavity a tilling so tight as to 
exclude germs, and so decay is stopped. As you 
observe teeth, note whether you find the cavities 
and fillings more often at the edges or at the fronts 
of the teeth. Why is this so? 

The saliva. By means of the saliva starch is 
chemically changed into a form of sugar called 
maltose. Only a small part of the starch we eat 
has time to change to maltose under the influence 
<»f saliva; the remainder must be digested in the 
intestine. 

t. When the flow of saliva is checked through fear, 
embarrassment or some other emotion, how does the 
mouth feel? 

2. How is speech affected? 

3. How does saliva assist mechanically in swallowing 
food? 

4. Hbw many uses of the saliva can you enumerate? 

The secretion of saliva. The saliva is secreted 
by three pairs of glands. Thelargesl (parotid) lies 

below and in front of the ear, another (submaxil- 
lary) lie- near the angle of the jaw, and the third 



i66 



PHYSIOLOGY AND HYGIENE 



(sublingual) near the center of the floor of the 
mouth under the tongue. The duct from the paro- 
tid gland opens in a little projection in the cheek. 
Look for it, using a mirror. Observe near which 
tooth it is. The other ducts open in a small ridge 
on each side under the tongue. Look for the 
ridge, using a mirror. In Figure 50 you can 
see that the cells of the gland are well supplied 
with fluid from the blood vessels. The cells take 

in this fluid on one side, 
and from it produce 
saliva, which they exude 
into the duct on the 
other side. 

The tongue. Nerves 
of taste end in the pa- 
pillae of the tongue, and 
also in the roof of the 
mouth. Taste is not an 
infallible guide in eat- 
ing; it does not enable us always to distinguish 
harmful things from wholesome foods. But it does 
enable us to some extent to choose the good; for 
when we have once learned the taste of sub- 
stances we can identify them by tasting. A very 
important function of taste is to stimulate the 
secretion of digestive fluids. When things taste 
good more saliva and gastric juices are secreted, 
and so digestion is promoted. 




SECRETING 
CELLS 



ARTERv 

Fig. 50. Diagram of a 
small portion of a gland, 
much magnified. 



DIGESTION 167 

1. What does the tongue do when we chew? 

2. Examine a small pieee of lamb or hog tongue from 
the meat market; of what kind of tissue is it composed? 

3. Looking in a mirror, compare the upper with the 
under surface of your tongue. 

4. There are three kinds of papillae on the tongue. 
The fungiform are seen as small red spots; the filiform 
are light colored. Which are more numerous? 

5. The circumvallate papillae lie far back on the 
tongue, are red and large. How many of them can you 
see? 

6. What does the tongue do when you swallow? 

Swallowing. When the tongue has pushed the 
food back into the pharynx (see Figure 37), the 
muscular walls of the latter contract and squeeze 
the food into the esophagus. The circular muscles 
of the esophagus then . „ 

contract successively, ven * cav * 
beginning at the top, 
and so force the food 
ahead of the contract- 
ing rings into the 
stomach. Observe Fl(; _, ^ nilllilllc cr? s S 

the process in the section of the abdomen, showing 

the peritoneum lining the wall ol 
throat of a horse the cavity and folding back over 
... .... r ... the stomach, intestine and liver. 

while drinking. 1 he 

movements of the mouth and the beginning of 

swallowing are voluntary processes, but most of 

the swallowing and all the subsequent digestive 

movements are involuntary. It behooves us, then, 




1 68 PHYSIOLOGY AND HYGIENE 

to do well the part of digestion we control. Chew 
the food thoroughly, especially raw vegetable 
foods. Do the grinding in the mouth and so 
lighten the work of the stomach. Taste the food 
and enjoy the taste. Mix it with saliva to make it 
swallow easily; never wash a mouthful of food 
down with gulps of liquid. The practice is bad 
from a hygienic as well as from an aesthetic point 
of view. 

The peritoneum. The smooth, glistening, moist 
membrane lining the abdominal cavity is the peri- 
toneum. From the back it folds over the organs 
of the abdomen, forming their outer or serous coat. 
The digestive tract is, therefore, suspended by a 
double fold of peritoneum, which in this location is 
called the mesentery. Between these folds lie the 
blood vessels, lymphatics, nerves and fat. The 
mesentery has the appearance of a single instead 
of a double membrane. From the lower surface 
of the stomach the covering membrane loops down 
in front of the bowels like an apron. It is called 
the omentum, and it serves for the storage of fat. 
The mesentery supporting the twenty-five or thirty 
feet of intestine is attached to the body wall in the 
upper part of the abdominal cavity, so that the 
organs hang loosely suspended in the cavity; and 
from this center of attachment the blood vessels, 
lymphatics, and nerves radiate. This loose suspen- 
sion of the bowels and their smooth serous cover- 



DIGESTION 



169 



ing* give the loops of the intestine perfect freedom 
of motion on each other. 

The stomach. In Figure 52 the stomach is 
viewed from the front. The lining of the stomach 
is a mucous membrane, continuous with that of 
the esophagus and mouth. It is too large to fit 
the stomach and is, therefore, thrown into long 
folds running lengthwise of the organ. This mem- 
brane secretes a digestive fluid, the gastric juice. 
To give more surface for secreting cells, and so 
increase the secretion, the mucous membrane dips 
down into the under- 
lying spongy tissue in 
many little pockets 
called gastric glands. 
(See Figure 54O Be- 
neath the cells of the 
mucous m e m brane 
are blood vessels, 
lying in the spongy, 
fibrous sub-mucous 
layer. Next comes a 
layer composed of bands of muscle running in dif- 
ferent directions. Outside of all is the serous cov- 
ering. 

Stomach digestion. The muscles of the stomach 
have 3 gfeal deal of work to do in preparing the 
food for the intestine. While the mass of food is 

held in the pouch (to the left), a portion i^ 




ICREATIC 
OUCT 



Fir,. 52. Stomach and pan- 
creas, with ducts from the liver 
and pancreas joining as they en- 
ter the intestine. 



170 



PHYSIOLOGY AND HYGIENE 





squeezed off by muscular contraction and worked 
down to the pyloric end of the stomach, where it 
is moved slowly back and forth (see Figure 53) 
till it is well mixed with gastric juice and made very 
watery; then it is squeezed through the pylorus 
into the duodenum. The pylorus is kept closed by 
a ring of muscle which remains constricted while 
the food is being moved about in the stomach, but 
opens occasionally when food is suit- 
ably prepared to pass on. When 
the stomach digestion is finished, a 
strong contraction of the muscles 
will force through the pylorus the 
lumps that have resisted the action 
of the gastric juice. 

Gastric juice. Like the other di- 
gestive fluids, the gastric juice is 
nearly all (99.4%) water. Dis- 
solved in the water are the digestive 
substances, the chief of which is 
pepsin. It is sometimes extracted 
from the stomachs of freshly slaugh- 
tered animals and used in pepsin 
gum and pepsin tablets. Another 
substance is rennin; which is obtained from the 
calf's stomach and used to curdle milk in cheese- 
making. It has the function of curdling milk in 
the human stomach. Would you expect it to be 
more abundant in the stomach of a child or of an 




Fig. 53. X- 
ray of the con- 
tents of the 
stomach, show- 
ing the con- 
tractions o f 
the stomach 
muscles to 
"churn" and 
e x p e 1 1 the 
food. 



DIGESTION 171 

adult? Hydrochloric acid is also present in small 
amount, and is an indispensable constituent of 
gastric juice. The pepsin and hydrochloric acid 
act on nitrogenous foods, dissolving them and 
bringing them to suitable chemical conditions for 
assimilation. 

If a piece of lean meat is taken into the stomach, 
the gastric juice comes in contact with its surface. 
dissolves the cell walls and the protoplasm within 
the cell, and a considerable amount of the connect- 
ive tissue between the cells. The lump of meat 
goes to pieces; but there usually remains undis- 
solved a few shreds of tough connective tissue. 
Fat meat consists of a network of connective tissue, 
holding the cells of protoplasm distended with oil. 
The gastric juice digests the protoplasm and con- 
nective tissue, and so frees the oil, which becomes 
emulsified — scattered in very small drops through 
the watery fluid. 

A piece of vegetable has woody cell walls which 
the gastric juice cannot dissolve. If swallowed in 
a lump, it i> likely to remain a lump in the stomach 
and through the intestines. The gastric juice may 
get through the walls of the cells near the surface 
of the lump and digest out the nitrogenous mate- 
rial^, but most of the mass will remain undigested. 
Cooking and chewing disintegrate the mass and 
break the cell walls, so the contents of the cells 
can be thoroughly digested. 



172 PHYSIOLOGY AND HYGIENE 

The time of digestion. The length of time that 
some common foods remain in the stomach is 
given in the following table. The food is not, when 
it passes on into the intestine, fully digested. The 
fats are emulsified but chemically unchanged, the 
starches and sugars are very slightly affected by 
the saliva, and even the nitrogenous foods are only 
partly -digested. 

Hours Hours 

Beef, roasted or broiled. . . 3 Oysters, raw 3 

fried 4 stewed 3^ 

Mutton, boiled or broiled. . 3 Milk, boiled 2 

roasted 3^4 ra w 2% 

Pork steak, broiled 3% Beans, in pod, boiled 2 l / 2 

roast 5*4 Potatoes, baked 2 J / 2 

Brains, boiled i«)4 boiled y/ 2 

Chicken, boiled or roast. . . 4 Cabbage, raw 2V2 

Trout, boiled or fried i l / 2 boiled 4^2 

Bass, broiled 3 Turnips, boiled 2> l / 2 

Eggs, raw 2 Rice 1 

soft boiled 3 Bread, corn 3 T 4 

hard boiled or fried s J / 2 wheat 3J/2 

The foods that remain long in the stomach are, 
as a rule, difficult to digest. In fact, difficult to 
digest means little more than taking a long time, 
together with its logical accompaniments, the use 
of more gastric juice, more muscular energy, and 
more chance for fermentation. Foods digested in 
a short time are preferable, especially for people 
having difficulty with digestion. Most people who 
take plenty of outdoor exercise do not need to 
avoid a food because its time of digestion is long. 



DIGESTION 



i/3 



There are individual differences in the time of 
digesting foods. We have to learn, by trying, 

whieh kinds of food we can easily digest and which 
we cannot; and yet people, whimsical about their 
eating, are more often deranged in their imagina- 
tion than in their stomachs, and do not really need 
to refrain from the things the}' avoid. 

Cooking. The purpose of cooking is to make the 
iin)(\ more palatable and more digestible, and to 
kill the germs and parasites. Cooking foods to 
improve their tastes will not be considered here. 
Most harmful germs and parasites are killed by 
the temperature of boiling water, therefore if food 
is cooked thoroughly it is made sterile. Meat from 
an animal in sound health is wholesome and most 
easily digested raw. But occasionally a diseased 
animal is slaughtered and sold. Thus raw T meat 
sometimes contains live bacteria of disease. Some 
diseased pork contains tiny worms (trichina) in a 
resting stage. When taken into the stomach alive, 
they become active and produce thousands of 
young, which spread through the body, settling in 
the muscles and producing a very painful and some- 
times fatal illness. The tapeworm is another para- 
imbedded, in a resting Stage, in certain diseased 
beef and pork. If this meat is eaten raw the para 
site may lodge and grow in the human intestine. 
It rarely produces serious re-ults, and i^> removed 
without difficulty. 



174 PHYSIOLOGY AND HYGIENE 

The bacteria of decay, whose growth in meat 
makes it tainted, produce poisons called ptomaines. 
Cooking the meat kills the bacteria, but does not 
render harmless the ptomaines. Tainted meat, 
spoiled ice creams, and other substances containing 
ptomaines can in no way be made fit for eating. 

One effect of boiling vegetables and dry grains 
is to make them soft, so that they can be chewed 
fine. The time required differs for different foods. 
When the food is soft it is sufficiently cooked. 
Boiling also causes the starch grains to absorb 
water, to swell and become permeable to the 
digestive juices. Cooked starch is much more 
digestible than raw starch. In flour and meal the 
starch is more accessible to the water because it is 
either broken out of the cells, or the cells are only 
a few in a small lump, so a shorter time of boiling 
is required. Moist vegetables like potatoes may 
be either boiled or baked; there is enough water 
in them. Dry things like rice or oatmeal must be 
boiled or steamed, and the water on them should 
be enough to make the grain soft, else they are not 
perfectly cooked. Sugary fruits and vegetables are 
cooked chiefly to make the woody parts soft. The 
less cooking lean meat has the more easily it is 
digested, but the tough parts of meat, the connect- 
ive tissues, are made soft only by being subjected to 
moist heat for two or three hours or more. Four or 
five hours is not too much for soup meat. Eggs are 



DIGESTION 175 

more easily digested raw. If they are cooked at a 
temperature a few degrees below the boiling point 
the}" will be more easily digested than if boiled. 
Omelet is easily digested, fried eggs are not. 

Pasteurization. Raw milk tastes better than 
boiled milk and it is more easily digested by chil- 
dren. Boiled milk often causes constipation. But 
the clanger from raw milk is that it usually con- 
tains an enormous number of bacteria. It has been 
found that heating to a degree considerably below 
the boiling point kills practically all harmful germs 
and does not have the objectionable effects that 
boiling has. This heating is called Pasteurization. 
The best method is to heat the milk at the bottling 
factory, to a temperature of 140 or 160 degrees, for 
about half an hour, then cool quickly, put in ster- 
ilized glass bottles and keep cool until used. Pas- 
teurization can easily be done in the home by the 
following procedure: Place the bottle of milk in a 
pail, on a saucer or something to hold it off the 
bottom; pour warm water around it to within two 
inches of the top (keep the stopper on all the 
time ) ; bring the water to a boil (of course the milk- 
is not boiling); immediately remove the bottle; 
cool it and keep it cool. 

Raw milk is very likely to give bottle-fed babies 
an intestinal infection which is frequently fatal. 
This is largely avoided by Pasteurization. Even 
boiled milk is better than raw milk for sick babies. 



176 PHYSIOLOGY AND HYGIENE 

Alcohol. There is very little absorption of water 
or of digested food in the stomach. But certain 
fluids, among them alcohol, are largely absorbed 
in the stomach. They pass directly through the 
mucous membrane and enter the capillaries, from 
which they quickly pass into the general circula- 
tion. Thus the effect of alcohol can be noticed 
within a few minutes after a drink is taken. 
Some people are in the habit of drinking a glass 
of wine with their dinner, to hasten the digestion 
of the food. Authorities are not altogether agreed 
as to the effect of a small quantity of alcohol thus 
taken; they rather generally concur in the opinion 
that the habitual use of alcohol with meals is un- 
hygienic. A large quantity of alcohol, especially 
of strong spirits, is exceedingly harmful to the 
mucous membrane. It produces congestion and 
abnormal secretion of mucus (catarrh), which in- 
terferes with digestion. In old topers the mucous 
membrane is often covered with ulcers, and is 
usually so thoroughly deranged that it is unable 
to fulfill its function. There is almost no stomach 
digestion in such cases. 

Tobacco. Tobacco produces vomiting; it is an 
emetic, as many boys know. The stomachs of 
those accustomed to its use have become so dulled 
by its influence that they do not reject the poison 
when taken in the ordinary small quantity. The 
impaired sensitiveness of the mucous membrane 



DIGESTION 



177 



extends to other things besides tobacco. Students 

in a dissecting room, workers in fertilizer factories 
and tanneries, find the stenches less intolerable 
when they use tobacco. The mild food stimuli, so 
important to digestion, have little effect on a stom- 
ach dulled by tobacco. 

Intestinal digestion. The food, mixed with gas- 
tric juice, passing from the stomach to the small 
intestine is called chyme. It is composed of very 
fine particles, partly digested and mixed with so 




LONGITUDINAL 




MUSCULAR 
COAT 



Fig. 55. A cross section of the wall of 
the small intestine, magnified. 

much fluid that it has a thin con- 
sistency and moves along the intes- 

Fk; : 54 A Ion- t j ne eas jiv The intestinal walls are 
gitudinal and J 

a cross section like those of the stomach in that they 

of a gland 

which produces have a mucous lining containing 
RS Jfe secreting glands (Figure 54), a sub- 
fiefL mucous layer, a muscular layer of 

circular and another of longitudinal fibers, and a 
serous covering (Figure 55). The mucous layer is 



i;8 PHYSIOLOGY AND HYGIENE 

longer than the other layers, and is therefore 
thrown into folds across the tube. These folds par- 
tially disappear when the intestine is distended. The 
surface of the mucous membrane is further in- 
creased by the villi, minute projections like the fin- 
gers of a glove, which project into the intestinal 
cavity. (See Figures 55 and 56.) As the acid 
chyme comes into the intestine, its presence stim- 
ulates the mucous membrane to secrete a fluid 
called intestinal juice. From the gall bladder and 
liver a stream of bile comes to join the chyme, and 
from the pancreas comes the pancreatic juice, the 
most important of all the digestive juices. These 
fluids are all alkaline. 

The intestinal juice is very similar to saliva in 
its digestive action, changing starch into maltose. 
It also changes maltose and common sugar into a 
simpler kind of sugar, glucose or grape sugar. 
This is ready for the protoplasm and is found all 
through the body. The bile assists in the digestion 
of fat. The pancreatic juice acts on all kinds of 
food. It contains at least three digestive ferments, 
one to act on sugars and starches, one for the 
nitrogenous foods, and one for fats. 

The food in the intestine is "worked," squeezed 
back and forth and mixed with the digestive fluids, 
by the action of the muscles in the wall of the 
intestine. At intervals a peristaltic wave passes 
along a section of the intestine, 'sending the food 



DIGESTION i 7 g 

along several inches. This wave is in appearance 
like the crawling movement of an earthworm. It 

is caused by the contraction of one portion after 

another of the muscular walls. The food is again 
worked by muscular contraction and again sent for- 
ward by another peristalsis, and so on. The chem- 
ical changes of digestion are proceeding all this 
time, and some of the digested food is being ab- 
sorbed. It usually requires several hours, eight or 
ten, for a stomachful of food to pass through the 
small intestine. 

There is a flap of mucous membrane at the open- 
ing from the small intestine into the large, which 
makes difficult a return movement of the contents 
of the large intestine. The small intestine is about 
as large as the thumb, while the diameter of the 
large intestine is about twice as great. The colon 
has frequent constrictions, which partially divide 
it up into little bays. The structure of the walls 
is practically the same as that of the small intes- 
tine, but there are no villi. The glands secrete, 
instead of a digestive juice, a slimy mucus which 
makes the contents of the tube move more easily. 
The food enters the large intestine thin and watery. 
A- it is forcer! along by occasional muscular con- 
tractions the digestive process is concluded and 
the liquid absorbed, leaving the contents of the 
lower colon and rectum thick and firm. Although 
the large intestine is Only about five feet long, the 



l8o physiology and hygiene 

food takes as much time to pass through it as 
through the twenty feet of small intestine. After 
the liquid has been absorbed from the intestine, 
there remains in the tube the woody parts of the 
vegetables we eat, hard, resisting bits of meat, and 
brown-colored waste from the bile. This material 
is called the feces. 

1. Why has the large intestine a greater diameter than 
the small ? 

2. Why are the walls of the colon wrinkled in deep 
folds? 

Intestinal hygiene. It is of the utmost impor- 
tance that the colon should not become clogged 
with fecal matter. It should be emptied at a regu- 
lar time every clay. If a generous amount of food 
is eaten, some of it usually escapes digestion and 
so remains unabsorbed in the colon. The condi- 
tions necessary for the growth of bacteria are here 
present, — warmth, moisture and food. The gas- 
tric juice is acid and kills most of the bacteria which 
are taken into the stomach; but all the juices of 
the intestine are alkaline and therefore provide a 
medium favorable to the growth of germs. There 
are always some bacteria present in the intestine, 
often producing as they grow offensive gases and 
sometimes poisons. If the bowels go unemptied 
two or three days, the quantity of poisons pro- 
duced and absorbed is so great ks to cause, a dull 
feeling, often headache, sometimes a high fever. 



DIGESTION iSi 

This is called auto-intoxication, and may become 
a serious matter if the neglect is prolonged. Do 
not go to advertised medicines for relief, but con- 
sult a reliable physician. Massage of the abdomen 
may stimulate the movement of sluggish bowels. 
Proper exercise and suitable diet will do a great 
deal toward keeping the bowels active and in good 
condition. Fruits, large amounts of water, and veg- 
etable foods with much woody substance are espe- 
cially recommended to people who suffer from 
constipation. 

Drugs. Since alcohol is so largely absorbed in 
the stomach, it comes to the intestine in a very 
dilute form, and does not have such a ruinous effect 
on the mucous membrane. It often produces an 
increased secretion of the digestive juices, but 
these secretions are not normal and do not have 
perfect digestive function. Though brandy is used 
a- a cure for diarrhea, persons addicted to the 
excessive use of liquors usually suffer from a severe 
diarrhea. How does the blood circulation of the 
liver make that organ especially exposed to the 
attacks of alcohol? Two forms of change in the 
liver tissue are common, and both seriously impair 
it- work. First, the protoplasm in the secretin;.; 
liver cell- may be partly replaced by fat; and sec 
ond, the cells may completely disappear and be 
replaced by scar tissue (cirrhosis). Opium dimin- 
ishes the >ecretion of all the digestive juices, and 



182 



PHYSIOLOGY AND HYGIENE 



so weakens the muscular activity of the digestive 
tract as to result in serious constipation. 

Absorption of food. The absorbing surface of 
the small intestine is much increased by the villi. 
These are about 1/25 of an inch in length and arc 
thickly distributed over the surface. In absorption 
the food must first go through 
the cells which cover the villus 
and make the compact lining of 
the intestine. The food enters 
the cells not simply by soaking 
in, but the cell walls are so thin 
and permeable that the proto- 
plasm is practically in contact 
with the food and by its own ac- 
tivity helps take it in, in much 
the same way as white blood 
corpuscles take in bacteria. 
When the food enters the cells 
of the mucous membrane, not 
all parts of it are in the chemical 
forms required for assimilation. 
Some of it is changed during its 
passage through the cells of the membrane, some 
is changed in the liver, and some perhaps in the 
lymph glands and in other places in the body. From 
the cells the food is passed into the interior of the 
villus, where most of the watery part, the nitroge- 
nous substances and sugar, is taken into the capil- 




Fig. 56. Diagram 
showing two villi, 
the one at the right 
with the capillaries 
removed to show 
clearly the lacteals. 
A lacteal network 
and blood vessels are 
in the submucous 
coat also. 



- -^ DIGESTION 183 

laries, passing thence through small veins to the 
portal vein, which distributes it to the liver. From 
the capillaries of the liver the hepatic veins collect 
the blood, containing fresh food, and carry it to the 
ascending vena cava, which conducts it to the 
heart. The oily part of the food does not easily get 
into the capillaries, but it is readily taken up by 
the lymphatics, here called lacteals. Small muscles 
in the villi occasionally contract and squeeze the 
fluid contained in the small lacteals into larger 
tubes which convey it to the thoracic duct (cisterna 
chyli), through which it is carried to a vein in the 
neck and with the blood goes on to the heart. 

The lacteals get their name from the milk-col- 
ored fluid, chyle, which they carry. 

1. Put a few drops of some nearly colorless oil (olive 
or sperm) into a bottle half full of water and shake it 
vigorously, making an emulsion. How does it change 
by standing a few minutes? 

2. Add a little bile or mucilage and shake again. Is the 
emulsion more or less transient than at first? 

3. Why does chyle look white? 

4. Trace the route along which each of the following 
foods goes, after it is digested, to get to the heart : sugar, 
lean meat, butter, starch, cheese, potato, fat meat. 

Fats. The necessity for any chemical change in 
fats may not at first be apparent. It is already a 

fluid in the Stomach, and it i> in a suitable chemical 
condition to circulate in the blood and be 
assimilated. The problem is to get the fat through 



184 PHYSIOLOGY AND HYGIENE 

the watery mucous membrane. Soap is commonly 
made by boiling fats or oils in alkalies. The 
digestive juices in the intestine are alkaline. At 
least part of the fat is, in the intestine, changed to 
soap, which readily dissolves and is absorbed 
through the watery membrane. Some of the fat is 
split into fatty acids and glycerine, both of which 
are easily absorbed. The soap, fatty acids and 
glycerine are, to some extent, perhaps completely, 
recombined in the cells of the mucous membrane 
into fat. The tiny drops of fat can, under the 
microscope, be seen in and behind the cells. They 
pass on into the lacteals. Some of the fat, also, is 
generally supposed to be absorbed as oil, through 
the activity of the protoplasm of the cells covering 
the villus, and probably under the influence of a 
coating of bile and pancreatic juice. 

Resume 

i. Which class of foods do civilized people use most? 

2. In the digestive process, starch is changed into 
what ? 

3. Name the fluids that work this change, and state 
where each is produced. 

4. By what fluids is sugar digested? 

5. Nitrogenous foods are digested by what fluids? 

6. Where is each of these fluids produced? 

7. Name the juices involved in the digestion of each of 
the following foods : bread and butter, eggs, roast pork, 
oatmeal with sugar and cream, mince pie, beef steak, pork 
and beans. 



DIGESTION jgs 

Function of the liver. The bile is a very com- 
plex fluid. It assists in the digestion of fat. It is 
in part nitrogenous material that can be used again 
in the chemical activities of the cell, and in part 
substances probably altogether useless to the body. 
As the bile passes along the intestine there is oppor- 
tunity for the useful part to be absorbed and enter 
the blood again. The useless substances are mostly 
in small brown or yellow grains, and though some 
are absorbed the remainder are discharged with 
the undigested fragments of food. Besides the 
work of excreting bile, the liver has other very 
important work to do. When the blood from the 
portal vein, containing much sugar just absorbed, 
comes into the capillaries of the liver, the liver 
cells take out a large part of the sugar and turn it 
into glycogen, almost like starch, which they store 
up in themselves. Then when the sugar in the 
blood is used up by the protoplasm of the body and 
there is no supply coming from the intestines, the 
glycogen is gradually turned back to sugar and is 
taken up and carried through the body by the 
blood. This is a very simple process, since the 
difference between glycogen (C 6 H 10 O 5 ) and sugar 
(C 6 H 12 O e ) is slight. Consider what must be taken 
from the sugar to change it into glycogen. Gly- 
cogen is produced from nitrogenous foods also, 
when there is more nitrogenous food in the blood 
than is needed to replace the proteid waste. In 



186 PHYSIOLOGY AND HYGIENE 

this action there results a nitrogenous residue 
called urea. Also, the nitrogenous waste produced 
in the breaking down of protoplasm comes to the 
liver in the general blood circulation, and is there 
split into glycogen and urea. The latter is of no 
further use in the body and is removed by the 
kidneys. 



CHAPTER XI 
THE SKIN 

Imagine the body without a skin, the moist mus- 
cle and connective tissue exposed to the air. The 
lymph would ooze out and dry and the cells of the 
tissues that lie at the surface would die. 

How would the surface thus exposed be affected 
by the clothing- and by other objects that touch it? 
State another need of skin. 

We can handle arsenic and many other chemical 
poisons without being injured. How would it be 
if we had no skin? State another need of skin. 

How would the body be affected by the bacteria 
that touch it if we had no skin? What further 
use, then, have we for a skin? 

Besides serving these ends, the skin is the chief 
means of regulating the temperature of the body 
and it contains the organs at the ends of the nerves 
by which we have the sense of touch and of tem- 
perature. We must now see how the structure of 
the skin fits it for these uses. 

Epidermis. Study Figure 57. 

1. What two genera! parts or layers has the skin? 

2. Of what is the outer part composed? The inner 

187 



i88 



PHYSIOLOGY AND HYGIENE 



layer is chiefly composed of fibers, which serve as a sup- 
port for the blood vessels, nerves, glands, fat, etc. 

3. Are any blood vessels shown in the epidermis ? 

4. How can the epidermis be provided with the condi- 
tions necessary to life if it has no blood vessels? 

5. If the oxygen and food had to come to these cells 
from the dermis, which cells would get the larger supply ? 

6. What would be the fate of cells removed several 
tiers from the source of supply? 



STRATUM CORNEUM 




^SEBACEOUS GLAND 

FAT CELLS 
SWEAT-GLANDS BLOOD-VESSELS 

Fig. 57. A section of the skin, highly magnified. The stratum 
corneum is the scaly surface continually wearing off. The papillae 
contain the nerves of touch. 

As might be expected, the growing cells are at 
the bottom of the epidermis. As they increase in 
number, some cells are crowded away from the 
source of supply and become thinner and dryer till, 
at the surface, they become hard scales. The old 
scales are constantly being worn and washed off 
as the new form under them. The protoplasm of 
the outer cells, before it dies, produces a waxy 
substance that renders the cells hard and nearly 
impervious to water and germs. 

Dermis. Examine with a magnifying glass the 
torn edge of a piece of leather. The threads seen 



THE SKIN 189 

are the fibers of the dermis. In the preparation of 
most leathers the epidermis is rubbed off and the 
inner part of the dermis scraped and shaved away, 
leaving little more than the compact fibers of the 
skin. A tanner says the skin is stronger than the 
leather made from it. Beneath the skin, or, per- 
haps more exactly, forming the deeper part of it, 
is a loose fibrous tissue (subcutaneous) which con- 
nects it with the underlying tissues. In the deeper 
part of the dermis and in the subcutaneous tissue 
are groups of fat cells. They serve as a pad and 
help protect the body from blows. They also 
make the skin smooth and plump. 

1. Does a girl usually have more or less fat under the 
skin than a boy? 

2. In old people the fat is largely absorbed from be- 
neath the skin ; what appearance does this give to the 
skin? 

3. Which part of the skin serves as a water tight cover- 
ing to keep the moisture of the body from oozing away 
or evaporating? 

4. Which part of the skin provides the mechanical 
strength for protecting the underlying tissue from blows 
and tears? 

5. Which part thickens where there is much chafing 
and wear, a- in the palms of the hands and the soles of 
the feet? 

Stick a pin slanting into the callus. How do you 
know which part i^> here thicker? 

7. Which part of the skin protects us against chemical 
and bacterial poison- ? 



190 PHYSIOLOGY AND HYGIENE 

8. Thousands of bacteria get lodged on the skin every 
day; what becomes of them as the epidermal scales 
fall off? 

The sweat glands. The minute tubes opening at 
the surface of the skin are called sweat glands. 
The tube in diameter is 1/60 to 1/80 of an inch. 
Though it reaches only to the bottom of the dermis, 
its length is much greater than the thickness of the 
skin. 

The cells are epidermal in their origin, though 
they extend into the dermis. They take the fluid 
from the blood and from it produce the perspiration 
with which they fill the tube. The perspiration is 
more than 99% water, dissolved in which are some 
salts and waste matter. Its chief function is the 
regulation of the temperature of the body, but it 
is also an excretion. 

1. By what form does the tube of the sweat gland get 
considerable length without extending very deep? 

2. Does this form make it easier or more difficult to 
supply the cells composing the wall of the tube with fluid 
from the blood vessels. 

3. Examine the tip of the finger with a magnifying 
glass. Are the pores, the openings of the sweat glands, 
located along the ridges, or in the grooves? 

4. Pinch and rub the finger, clasp it in the other hand, 
or hold it in hot water for a minute and then dry quickly, 
to see if you can make the perspiration appear at the 
pores. 

If you can get droplets of perspiration on the back of 
the hand or fingers, describe the arrangement of the pores. 



THE SKIN 



191 



Touch the palmar surface of the last joint of each 

finger to an ink-pad and then to the page of your note 
hook. Better than an ink-pad is a piece of glass on which 
printers 1 or engravers' ink has been thinly spread with a 
pad or roller. Wash the ink off your finger with a rag 
soaked in gasoline. 

5. Is the arrangement of ridges exactly the same on all 
the finger^ ? 

6. Are any two ringer prints altogether alike? 

7. In what particulars are they all similar? 

8. Describe the surface of the back of the finger seen 
under a lens. 

The hair. Like the sweat glands, the hair is epi- 
dermal in structure; it grows from cells at the bot- 
tom of a follicle which 
dips down into the der- 
mis, but is lined with 
epidermal cells. The 
bulb from which the hair 
grows contains blood 
-els and nerves and 
is dermal, but is covered 





Fig. 58. A surface view of 
a portion of a hair, B — longi- 
tudinal section of the same, 
highly magnified. 



with epidermal cells. A tiny muscle is fastened to 
the root of the hair and, in the common animals, 
i< able by its contraction to stand the hair up 
Straight. The hair is a slender tube of hard dry 
cells packed and cemented together, the central 
part being filled with softer and more moist cells 
containing- coloring matter. Of course, the hair 
grows only at t lie lower end, where, it receives 



192 PHYSIOLOGY AND HYGIENE 

accretions from the live cells. The human hair is 
chiefly an ornament, though its protective func- 
tion, especially on the head, is considerable. The 
well-being of the hair depends on the healthful- 
ness of the scalp. Both hair and scalp should be 
washed regularly and the hair brushed vigorously 
but not harshly each day. Brushing and combing 
the hair brings the oil out to the ends of the hairs, 
rendering them less likely to become brittle and 
break. Animals shed their hair with the change 
of season, but human hairs drop out irregularly, a 
few at a time. If the bulb at the root of the hair 
is healthy, a new hair is produced, starting even 
before the old has dropped out. Often a poor 
growth of hair can be improved by treatment of 
the skin that produces it. A reputable physician 
should be consulted. There is no magic lotion or 
oil that will make hair grow. 

The nails. Like the hair, the nails of the fingers 
and toes are hardened epidermal cells. The light 
area at the base, with a curved border, is called 
lunula (little moon). The nail grows by accretions 
from the epidermal cells of the lunula and from 
those touching the covered root of the nail. Press 
on the pink part of the nail to see if it seems thicker 
in one place than another. The nails are useful in 
protecting the finger tips and in picking up small 
things. They stiffen the ends of the toes and so 
help in walking. They should be trimmed smooth, 



THE SKIN 193 

about even with the flesh tip of the linger; and the 
skin at the back of the nail should be rubbed gently 
back if it is stretched out by adhesion to the grow- 
ing nail. The nails trim best when softened by 
warm water. 

Baths. There are two distinct purposes in bath- 
ing. The warm bath is for the purpose of cleansing 
the skin. It should be taken just before going to 
bed, since it leaves the skin relaxed, the blood ves- 
sels dilated and in no condition to endure drafts 
and changes of temperature. The cold bath is a 
stimulus. It should be taken on rising in the morn- 
ing. The proper temperature of the water depends 
on the vigor of the bather; a man of rare vigor can 
stand it ice cold, but common hydrant water is 
severe enough for most persons. The cold bath 
should last for a minute or two, or even less, and 
should be followed by a brisk rub. The cold bath 
is a severe stimulus, beneficial to those who react 
well from it, but not advisable for others. Many 
people, in fact, are greatly injured by subjecting 
themselves to a treatment they cannot endure. A 
good plan is to begin with water slightly warm 
and change it gradually to as low a temperature as 
is bearable, then rub quickly until dry. For those 
who find the cold bath too severe, a sponge or dry 
rub may be beneficial. 

Temperature. The -kin has a very important 
function in the regulation of the temperature of 



194 PHYSIOLOGY AND HYGIENE 

the body. Heat is produced by the activities of all 
the organs, but chiefly by the muscles. The neces- 
sary activities of the body in work or play usually 
produce too much heat, so the temperature is 
brought to the proper degree by a cooling process. 
The regulation of the temperature consists chiefly 
in adjusting the rate of cooling to the rate at which 
superfluous heat is produced. In the cold, if our 
muscular activity is slight our temperature may go 
down, and the body has to bestir itself just to pro- 
duce heat; that is, we shiver. Generally, however, 
the regulative action is a process of cooling. 

The skin is cooled by imparting its heat to its 
surroundings through radiation and conduction, 
and by the evaporation of perspiration. The skin 
radiates and conducts its heat off much faster when 
it is very warm than when it is cool. If the body 
is too warm, the blood supply to the skin is in- 
creased, through the action of the vaso-motor 
nerves on the muscles in the walls of the vessels, 
the skin becomes very warm and gives off much 
heat. Some winter day when your fingers are cold 
and your body is aglow with exercise, hold your 
hand near your face and feel the radiating heat. 
If the body is losing too much heat, the blood ves- 
sels of the skin are made to contract, less blood 
can get to the surface, the skin becomes cooler and 
gives off less heat. 

The temperature of the skin is lowered also 



THE SKIN 



195 



through the evaporation of perspiration. Some 

perspiration is being produced nearly all the time. 
If the body is not too warm the amount of per- 
spiration is small and may dry as fast as it comes 
to the surface. If the body is too warm the sweat 
glands receive a nerve stimulus that makes them 
work faster, and the body is covered with per- 
spiration, the evaporation of which lowers the 
temperature. 

1. Put a drop of water on your hand, and near it a 
drop of ether, alcohol, chloroform or gasoline. Which 
evaporates more rapidly? Which feels cooler? Why? 

2. The mere presence of moisture on the skin would 
not cool it. Heat is used up in evaporating moisture. 
Does water evaporate more rapidly into a moist or into 
a dry air? 

3. Why does 85 degrees on a sultry day feel warmer 
than even 95 degrees on a dry day ? 

Clothing keeps the body warm by shutting ofif 
the currents of air which carry away the heat from 
the body, and also by checking the radiation from 
the skin. For very cold climates the outer cloth- 
ing should be of compact weave or of skins, to 
keep out the wind. Sudden changes in the tem- 
perature of the skin are harmful, therefore poor 
conductors of heat are better than good conductors. 
For this reason silk and woo] are more desirable 
than cotton or linen. In torrid deserts people wear 
heavy clothing to keep off the heated atmosphere. 



196 PHYSIOLOGY AND HYGIENE 

sometimes 100 to no degrees in the shade, and as 
a protection from the sun's rays, which have a very 
high temperature. In moist, torrid regions people 
wear a minimum amount of clothing. (They live 
largely in forest shade.) Explain fully the reason 
for the difference. 

Alcohol rubbed on the skin evaporates quickly 
and thus lowers the temperature of the skin rap- 
idly. This has a tonic effect. Athletes often rub 
down with alcohol and it is also employed to reduce 
the temperature in fever. Taken internally, alcohol 
causes the blood vessels of the skin to relax and 
become filled with blood. There is thus greater 
radiation and perspiration. Thus the body is 
cooled by alcohol. Polar explorers do not drink 
alcoholic liquors, and people addicted to its use 
have little power to resist cold. The temperature 
of an intoxicated man exposed to the cold has been 
known to be as low as 75 degrees, but this is 
unusual. 



CHAPTER Xll 

THE KIDNEYS AND THE DUCTLESS 
GLANDS 

The kidneys. The function of the kidneys is to 
remove from the blood substances that are not 
needed by the body. The chief of these is the 
nitrogenous waste. (See Figures 35 and 59.) No- 
tice the location of the kidneys in the body. Each 
is about five inches long. The secreting cells of 
the kidneys are arranged in tubes which lie in 
characteristic loops and coils. Around them are 
the blood capillaries. The secreting cells take in 
on one side, the lymph, and on the other side pour 
into the tube which they surround large quantities 
of water, holding in solution the various excretions 
of the kidney. The process of removing these sub- 
stances is, in part, a simple mechanical filtration, 
the blood pressure forcing some of the fluid 
through the cells; and it is, in part, accomplished 
by the action of the protoplasm in selecting certain 
substances from the lymph and leaving others. 
The kidneys do not produce urea, they merely lake- 
it out of the blood. The kidneys excrete, besides 
urea, some carbon dioxide, a variety of salts, and 
other substances, some of which are poison. The 

'97 



198 PHYSIOLOGY AND HYGIENE 

secreting tubes empty their secretion, urine, into 
a receptacle at the inner side of the kidney, from 
which the ureters convey it to the bladder. Thib 
is a muscular sack situated in the anterior part of 
the pelvis. It is lined with cells several layers deep, 
so that the contents of the sack may be little ab- 
sorbed. A single tube (urethra) carries off the 
urine from the bladder. A circular muscle at the 
outlet of the bladder, which can be voluntarily 
relaxed, closes the tube and so retains the urine 
within the bladder. 

The work of the kidneys is indispensable to the 
body. Like other organs of excretion, the lungs 
and skin, the kidneys do not need to work to their 
full capacity to carry off the wastes of the body. 
They can suffer considerable injury, and still do 
their necessary work. But if their power to work 
is lowered to the extent that they are unable to 
remove the poisonous wastes from the body, severe 
illness ensues, and unless the defect is remedied 
death is inevitable. 

Alcohol. One of the most pernicious effects of 
alcoholic liquor is the injury it does to the kidneys. 
In moderate drinkers, kidney disease is very com- 
mon. Some of the secreting cells are destroyed, 
and this compels those that remain to do overwork. 
Alcohol more than any other factor produces 
Bright's disease, which usually terminates fatally. 
Excessive drinkers nearly always have kidney dis- 



KIDNEYS AND DUCTLESS GLANDS 



199 



case. The light liquors, such as beer, in addition 
to the effect of the alcohol contained in them, injure 
the kidneys by the excessive quantity of water 
which is taken in the large drinks and which must 
be eliminated by 
these organs. They 
are overworked 
and wear out early. 
Internal secre- 
tions. The b o d y 
has several glands 
without ducts or 
other outlets for 
their secretions. 
The fluids they pro- 
duce must, there- 
fore, be turned back 
into the lymph and 
blood. One of these 
lies just above the 
k i d n e y , and so 
takes the name su- 
prarenal or adrenal 
gland. (See Figure 
59. ) The substance 
it secretes is a stimulus to the vaso-motor nerves, 
and is needed to keep them in proper tone. Adre- 
nalin is extracted from this gland in slice]) and is 
used in medicine to check hemorrhage and relieve 
congestion. 




Fig. 59. Diagram of the urinary 
system. U — ureter. Ur — urethra, A 
--artery. V — vein, S — suprarenal 
gland. 



200 PHYSIOLOGY AND HYGIENE 

Another such gland is the thyroid, which lies 
ventral to the upper part of the trachea. If the 
secretions of this gland are deficient, the cells of 
the body seem to lack their normal function of 
assimilation and oxidation and neither body nor 
mind develops fully. If the gland is enlarged 
(goiter) and produces too much secretion, the ac- 
tivities of the cells may be too great and rapid 
pulse, headache, and even insanity may result. 
Upon the first symptoms of enlargement of these 
glands a good physician should be consulted. 

The pancreas, in addition to its work of secreting 
a digestive juice, produces from special cells an 
internal secretion. This secretion seems to have a 
very important function in the regulation of the 
sugar supply in the blood. The liver (p. 185) and 
muscles convert sugar into glycogen and store it 
until it is needed, when they change it back to 
sugar and send it on in the blood. The normal 
amount of sugar in the blood is 2%. If the glyco- 
gen function is disturbed, or if the sugar is not 
properly built into fat or oxidized in the cell, the 
blood becomes overloaded. Then sugar is removed 
from the blood by the kidneys, and diabetes, or 
sugar in the urine, is the result. This disease is 
supposed, in at least a large number of cases, to 
result from failure of the pancreas to do its proper 
work. By careful treatment the trouble is often 
alleviated. 



KIDNEYS AND DUCTLESS GLANDS 201 

The spleen. The reddish In-own oblong organ, 
lying- at the left of the stomach, is the spleen. It 
has no duct ; if there is any secretion, it must be 
internal. The spleen is sometimes known as the 
largest lymph node. It is closely related to the 
lymph system, suffers when the lymphatics are 
diseased and produces white blood corpuscles, as do 
the lymph nodes. It is said to disintegrate the red 
blood corpuscles that have died. It is much swollen 
and sometimes permanently injured by malaria and 
typhoid. 



CHAPTER XIII 
THE SPECIAL SENSES 

We commonly speak of the "five senses" be- 
cause there were thought to be just five. We 
should add to these the muscular sense, the sense 
of heat, of cold, of pain, and possibly some others. 

The function of the organs of special sense is to 
receive impressions from the world outside the 
body and convert these impressions into nerve cur- 
rents. In the lowest groups of animals there are 
no sense organs and no special senses. All the 
protoplasm has the nervous function of irritability 
and responds to such influences as light, warmth 
and touch. Animals higher in the scale of devel- 
opment, which have well-developed nervous sys- 
tems, have also special organs to respond to the 
various outside influences, — ears to receive sound 
vibrations, to convert them into nerve currents and 
send them on to the brain; eyes whose sensitive 
part undergoes a chemical change when exposed 
to the light and so starts a current to the nerve 
centers; touch organs whose compression gener- 
ates nerve currents; organs of smell, of taste, and 
so on. When the sense organ translates the im- 
pressions from the outside world into nerve cur- 

202 



THE SPECIAL SENSES 



2 °3 



rents, the currents come to the brain. We have 
sensation only with brain action. 

' The highest classes of animals have these special 
senses in greatest number and most highly devel- 
oped. Yet not even man has sense organs to 
respond to all the forces of the world. We know 
electricity, magnetism, certain chemical rays from 
the sun, the X-ray, etc., not directly through sense 
organs, but by studying their effect on things we 
can sense. Xo one knows how many such things 
there are in the world, things we can never hope 
to gain direct knowledge of, because our sense 
organs are so limited. \Ye have no reason to think- 
that any of the lower animals have senses we lack, 
though some of them have certain senses more 
acutely developed. The dog can smell things not 
noticed by us; the eagle's eye is more powerful 
than ours; it is thought that some insects hear 
vibrations that are beyond the range of our ears. 

A. The Eye 

The eye. In the eye we find the same general 
principles of construction as in the camera. As 
you learn the parts of the eye, point out the corre- 
sponding parts of the camera. (See Figures 60 
and 6l.) The outer coat of the eyeball IS the 
sclerotic. This coat is tough and strong; it serves 
the framework and support for the active parts 



204 



PHYSIOLOGY AND HYGIENE 



of the organ. The part of it we see in each other's 
eyes is the white of the eye. 

1. Look from the side at the cornea of your neighbor's 
eye. Does it curve out more or less than the eyeball ? 

2. Is it all transparent ? 

3. Why should it be named cornea (horn) ? 

4. The part of the eye that gives it color — blue, brown, 



i SUSPENSORY 
LIGAMENT 



VITREOUS 






HUMOR 






RETINA ]jX 




CHOROID — Njpj^v 




SCLEROTIC ^%. 




COAT — ""^^f^ 


|jjE^g0 


mk 


fllr — ■ 0PT,C 






"'' NERVE 



Fig. 60. Section of the eye. 

gray, etc. — is the iris. Describe its colors in detail in 
your own or in your neighbor's eye. 

5. How large is the hole (pupil) in the center of the 
iris? 

6. Why should it appear black ? 

7. Have your neighbor face a bright light ; shade his 
eyes with your hand. While watching his pupil sud- 
denly remove your hand and let the bright light shine in 
his eyes. What change occurs in the pupils? 

The eye chamber is made dark by the choroid 
coat, a membrane filled with black granules, lying 



THE SPECIAL SENSES 



2Q- 



just inside the sclerotic coat. The aqueous humor, 
filling- the space between the lens and the cornea, 
is a thin water)- fluid. The vitreous humor is stiff 
like a soft jelly. The nerves enter the eye in the 

rear, pass through all three coats and spread out 
in the retina. The retina is a complex membrane 

composed of several layers, the outermost of which 
contains substances that decompose when exposed 
to light and in so doing generate nerve impulses. 
The ends of the nerves are most numerous in the 




Fie. 61. Diagram of the camera. D — diaphragm. P — plate, 
L — lens. 

back part of the chamber where the rays strike 
from directly in front, and so the eye is most sensi- 
tive there. Rays from an object at one side, which 
enter the eye slanting and strike upon the retina 
at one side of the chamber, produce but an indis- 
tinct image. Therefore, when we wish to give our 
attention to an object we turn our eyes directly 
toward it. 

The working of the eye. The manner in which 
the rays of light bend in going from the air into 



206 



PHYSIOLOGY AND HYGIENE 



the denser transparent substances determines the 
working of the eye. Rays at right angles to a 
surface do not bend at all. Rays entering obliquely 
a flat surface, as water or window glass, all bend 
the same amount, and so keep their former relation 
to each other. But rays entering a convex surface 
are brought toward each other, to meet at a point 
called the focus. (See Figure 62.) In the eye the 
cornea and the lens have the convex surfaces for 
focusing the light. From every point of the object 




Fig. 62. Rays of light through a lens, 
image at the focus. 



O — object, 1 — lens, f — 



seen, rays enter the eye and are brought to a focus 
on the retina. The very complicated nerve endings 
in the retina send currents to the brain whenever 
they are stimulated by light. If the rays are not 
brought to a perfect focus on the retina, those from 
one point overlap those from another, and the 
image is blurred and indistinct. This happens 
when the curvature of the cornea and lens is not 
adapted to the length of the eye. Rays nearly par- 
allel are brought to a focus nearer the lens than 
rays much diverging. 



THE SPECIAL SENSES 207 

1. Draw a diagram of the lens, and several rays to it 
from two points, one near and one farther away. From 
which point do the rays diverge more? 

2. If the distance from the lens to the retina is long, 
can near objects or far objects be seen better? When 
the eye is too long for the curvature of the lens and 
cornea the defect is short-sightedness. Objects can then 
be seen distinctly only when they are very close. 

3. If the distance from the lens to the retina is short, 
can objects near or far be better seen? If the eye is 
too short, the defect is long sight, inability to see things 
clearly that are very near. 

4. Does a grandmother hold a needle close or at arm's 
length to thread it? 

5. Is long sight common in young or in old people? 

Focusing. How is the focus in a camera ad- 
justed for objects of different distances? Since the 
length of the eye is unchangeable, the focusing 
must be clone in a different way. The more convex 
a lens is the more it bends the rays of light. The 
lens of the eye is changeable. It is fastened around 
the margin by fibers running to the >tiff wall of the 
eye. These elastic fibers are stretched, and there- 
fore exert a constant pull on the lens, tending to 
make it thinner. A ring of ciliary muscles ( Figure 
601 is fastened to the fibers so that when the mus- 
cles contract the fibers are drawn toward the lens, 
the tension is relieved, and the lens becomes more 
convex. The normal eye can adjust the focus from 
about eieht inches to an unlimited distance It is 



208 PHYSIOLOGY AND HYGIENE 

best for the eyes to have the book fifteen to 
eighteen inches away, and to look off occasionally. 

i. Would these muscles contract to adjust the focus 
to a near or to a far object? 

2. If your eyes are tired of reading why does it rest 
them to look at some object in the street? 

3. How near to your face can you hold a book and read 
it easily? 

The use of spectacles. Spectacles are used to 
compensate for several defects of the eyes. If the 
eye is short-sighted the rays that enter it must 
diverge much, as from a near object, if they are to 
focus on the retina. Therefore concave glasses are 
used, which cause rays from a distant object to 
diverge as much as they would from a near object. 
If the eye is long-sighted, the glasses are convex so 
as to make the rays less diverging, as though they 
came from a greater distance. 

One of the most common defects corrected by 
glasses is astigmatism. This is an irregularity in 
the curve of the eye, a curve like the side of an 
egg instead of the surface of a sphere, which results 
in only part of the rays focusing on the retina at 
once. Part of an object therefore appears clear 
while part is dim. 

External mechanism. The eye is turned in its 
socket by six muscles, fastened at one end to the 
eyeball and at the other end to the back part of 
the bonv socket of the eve. The muscle at the 



THE SPECIAL SENSES 



2Q[) 



right side of the eye contracts to turn the eye to 

the right, the muscle on the under side contracts 
to turn the eye down, and so on. By muscles fun- 
ning obliquely, the eye can be rotated. If the inside 
muscle (the side toward the nose ) is too short, it 
turns the eve inward so that it does not look 
straight forward when the other eye does; its line 
of sight crosses that of the straight eye. "Cross- 
eye" can often be corrected if treated carefully in 
childhood. The "wall eye" looks outward when the 
other is directed forward. The external muscles 
are too short. 

The moisture drains from the eye through a tiny 
tube emptying into the nose cavity. Look in the 
angle of the lids near the inner "corner" of the eye 
for the opening of this duct. If this duct is stopped 
up the moisture trickles out on the face beside the 
nose. A surgeon can usually open the duct again 
without difficulty. 

The skin is continuous over the eye. The part 
lining the lid and folded over the eyeball is called 
the conjunctiva. It is very thin and sensitive. If 
a particle of grit gets into the eye so as to produce 
irritation, and the tears do not readily wash it out, 
the lids should be raised or the upper lid turned 
back and the particle removed with a clean cloth 
or absorbent cotton. A burnt match from which 
the excess of charcoal has been rubbed off i> an 
client instrument for removing particles from 



210 PHYSIOLOGY AND HYGIENE 

the eye; it is soft and sterile. The upper lid can 
easily be turned back by pulling up gently on the 
lashes while pressing with a pencil on the thin 
skin behind the stiff border of the lid. 

A row of oil glands borders the lid, the secretion 
from which makes a barrier to prevent the mois- 
ture running over. A stye is an inflammation, 
often with pus formation, of one of these oil glands. 

i. If some object flashes toward your eye what do the 
lids do ? What is one of their functions ? 

2. Another use of the lid is to keep the eye moist. 
Hold your eyes open as long as you can. When the sur- 
face of the eye begins to get dry, a reflex nerve current 
compels the lid muscles to close the eye, moistening the 
surface. How often does this occur? 

3. The tear gland is located under the upper lid. When 
dust gets into the eye, what function have the tears ? 

4. In what part of the eye does the dust collect? 

5. How is the eye somewhat protected from blows of 
large objects? 

6. What protects it from dust? 

Blindness. Blindness is sometimes caused by 
derangement of the brain, sometimes of the nerve, 
sometimes of the lens, and sometimes of other 
parts. Some cases can be relieved by an operation, 
and some not at all. One of the most common 
causes of blindness is a contagious disease. The 
germs easily grow in the moist eye and produce an 
inflammation that may destroy the organ. Prompt 
treatment usually relieves the trouble; neglect is 



THE SPECIAL SENSES 211 

dangerous. New-born babes are so often affected 

by these germs that their eyes should be washed 
daily with an antiseptic In Egypt the house fly 
carries the germs and sore eyes are endemic. 

Care of the eyes. The eve is a very delicate 
instrument. With only ordinary care it does fairly 
well for people engaged in open, coarse occupations, 
but for those whose work requires continued close 
adjustment the eye needs especial care, and even 
then often proves deficient. The light by which 
we read should be adequate, but not very bright 
like the direct rays of the sun. It should come 
from above or from one side, so as not to shine 
into the eyes or reflect from the page into them. 
Most school rooms are so arranged that the light 
comes from above or from the left, that the shadow 
of the right hand in writing may be out of the way 
For reading, the light may well come from the 
right side. The page should be uniformly illumi- 
nated; cro*s lights with their shadows are to be 
avoided. If the eye is directed to one object a long 
time continuously, the focusing muscles become 
tired. Frequent glances from the page to some dis- 
tant object rest them. The distance at which a 
book is held is important. Twelve to fifteen inches 
is the best distance for steady reading, and we 
should take care not to vary much from it. 

Idle eyes are injured by dust, and should be pro- 
tected fr<»m it a- much a- possible. The germs in 



212 PHYSIOLOGY AND HYGIENE 

the dust are especially harmful. Inflamed eyes, 
with pus collecting in the corners, means germ in- 
fection. If the inflamed eyes are washed with a 
saturated solution of boracic acid, they usually 
recover quickly. Occasionally eyes are infected 
with virulent disease germs. Then they need the 
prompt attention of a physician and the use of a 
more potent antiseptic. Rubbing the eyes is one 
way of getting germs into them. The public towel 
or any other germ carrier is to be avoided. 

Defective vision is a very common, perhaps the 
most common, cause of headache. The strain of 
trying to see when one cannot see clearly causes 
the pain. The trouble is relieved by wearing suit- 
able glasses. If one suffers from chronic headache, 
it pays to have the eyes examined by a competent 
oculist. Glasses should always be worn when they 
are needed. 

B. The Ear 

Sound is caused by the vibration of the air. The 
vibration waves are caught by the external ear and 
conducted to the drum, a thin membrane which 
vibrates when struck by the sound waves. A chain 
of three bones carries the vibration to the internal 
ear, where it is translated to nerve currents and 
sent to the brain. 

The external ear. There is no apparent reason 
for the external ear having just the shape it has. 
So far as we can see, it would do its work just as 



THE SPECIAL SENSES 



213 



well if it were regular and less wrinkled. At the 
entrance to the ear canal, especially noticeable in 
men, are man) short stiff hairs which retard the 
entrance of insects The wax, produced by modi- 
fied sebaceous glands, is also an impediment to 
insects. If it is necessary to remove the wax, it 
should be done with a smooth, blunt instrument. 
care being taken not to scrape and irritate the ten- 
der skin and not to reach to the drum. Sometimes 




AUDITORY 
NERVE 



SEMICIRCULAR 
CANAL 



COCHLEA 

*f%. BASILAR 
2 MEMBRANE 



MEMBRANE 

HAMMER 

Anm x 



STIRRUP 



Fig. 63. Section of the car. 

the wax becomes hard and incrusts the drum, 
impairing the hearing. It can be removed by the 
use of warm soap suds and a syringe, but it is 
a rather delicate matter, and calls for the services 
• \ a physician. 

The middle ear. The air chamber lying between 
the drum membrane and the internal ear is the 
middle ear. The Eustachian tube connects it with 
the pharynx. Thus the air of the middle ear is con- 



214 PHYSIOLOGY AND HYGIENE 

tinuous with the atmosphere, and the pressure on 
both sides of the drum membrane is made the 
same. The lining of the middle ear and Eustachian 
tube is a mucous membrane continuous with that of 
the pharynx. AYhen the latter is inflamed and 
germ-infected, the infection is likely to spread to 
the ears. A serious earache often results from a 
bad cold. The fluid formed frequently breaks 
through the drum and discharges into the canal. 
This may be harmless, but often it injures the hear- 
ing. Sometimes this discharge through the broken 
drum is the means by which pus germs get into 
the middle ear. The pus may burrow into the 
porous bone surrounding the middle and internal 
ear, and may reach even the membranes surround- 
ing the brain and cause severe illness or death. A 
running ear should never be picked. It should be 
washed with sterile water only, and kept plugged 
with absorbent cotton. Every precaution should 
be taken to prevent infection. 

The bones of the middle ear are called the ham- 
mer, anvil and stirrup. The first is fastened to 
the drum, and vibrates with it. The second com- 
municates the vibration to the third, which is 
fastened to a membrane filling a "window" of the 
internal ear. 

The internal ear. The form of the internal ear 
is that of an irregular sack. From it branch three 
semi-circular canals lying in three planes, perpen- 



THE SPECIAL SENSES 215 

dicular to each other, and a "snail shell" (cochlea). 
All are hollow and filled with a watery fluid. This 
fluid touches one side of the membrane at the end 
of the bone chain, and thus receives the vibrations 
communicated from the air. In the cochlea is a 
vibrating membrane, wider near the base of the 
cochlea and narrower near the apex. This vibrates 
in harmony with the vibrations which reach the 
ear. the narrower parts of the membrane with the 
higher pitches, the wider parts with the lower. The 
auditory nerves terminate in special cells of this 
membrane. The vibration of the membrane sends 
nerve currents to the brain. Having a great num- 
ber of widths of membrane, each vibrating to its 
own pitch, we are able to distinguish between 
pitches. AYe are unable to hear vibrations that are 
either above or below the range of our membrane, 
but training will extend this range. Probably other 
animals may hear what we cannot. 

The semi-circular canals are not for hearing, 
but aid in maintaining the equilibrium of the body. 
Since the canals lie in three perpendicular planes, 
tipping the body in any direction alters the position 
of at least two of the canals. Stand erect, look 
straight before you a moment, then close your 
eye-. Can von stand steadier with your eyes open 
<>r clo^crl ? If the body begin- to move, the change 
in tlu- relative position of objects is registered by 
the eyes, and an unconscious muscular contraction 



2l6 



PHYSIOLOGY AXD HYGIENE 



is made to restore the body to its erect position. 
When the eyes are closed, we depend on the semi- 
circular canals to recognize the tipping of the body 
and to call for the muscular contraction needed to 
restore the position. Standing steady is an uncon- 
scious process, controlled probably by the cere- 
bellum. 

People who are deaf because of some affection 
of the external or middle ear, can still hear if the 



SKULL 
BONES 




OLFACTORV BULB 

OLFACTORY NERVE 
OLFACTORY 
NERVE 
BRANCHES 



PALATE 



Fig. 64. Section of the nose cavity, showing nerves of smell. 

internal ear can get the vibrations. If a thin piece 
of wood shaped like a fan is held against the upper 
teeth, the instrument catches the atmospheric 
vibrations and conducts them through the teeth 
and bones of the skull to the internal ear. 



C. Smell 



Observe over what part of the nasal cavity the 
nerves of smell spread (see Fig. 64). They end in 



THE SPECIAL SENSES 



21; 



olfactory cells which are exposed in the surface of 
the mucous membrane. Other cells of the mem- 
brane secrete a fluid which keeps the surface moist. 
A substance is smelled when minute particles of it 
floating in the air are brought in contact with the 
olfactory cells. How small a quantity of anything 
is rtquired to affect the organ of smell is illustrated 
by the fact that we can smell a perfume which is 




Fig. 65. Section of the mucous membrane of the nose, much 
enlarged, showing olfactory cells with hair-like projections. 

kept in a tight-stoppered bottle. Sniffing- simply 
increases the number of particles that strike against 
the mucous membrane of the nose. If you smell 
an odor constantly for an hour or so, is it stronger 
or fainter than at first: This means that some part 
of tlie smelling apparatus becomes exhausted and 
less active. While you are exhausted to one odor, 
are ymi sensitive to others, or does the exhaustion 
to one include all? A short rest (separation from 



2l8 PHYSIOLOGY AND HYGIENE 

the odor) restores the acuteness of the sense to 
the exhausting odor. 

The sense of smell is useful in helping us distin- 
guish substances when we have once learned their 
odor. Thus we are able sometimes to reject unfit 
food, and the odor of good food stimulates the 
digestive organs. Smell is impaired by inflamma- 
tion of the mucous membrane, as in a cold or in 
catarrh. Smoking injures the nasal membrane, 
and snuff-taking is especially harmful. 

D. Taste 

Taste is even more limited in its use than smell. 
When we get beyond the age of infancy, we are 
reluctant to put into the mouth to taste, things 
that are repulsive or unclean. Yet we do test them 
by smell. The flavor of foods is largely a matter 
of smell. The odor-giving particles rise from the 
mouth to the nasal chamber through the pharynx. 
If the nose is held during eating so as to prevent 
air currents from the pharynx from coming out, 
we lose most of the flavor of such things as onions 
and spices. There are four primary tastes — sweet, 
sour, bitter and salt. The hundreds of flavors are 
compounds of these and of odors. 

Taste cells are situated in taste buds, which are 
in papillae scattered over the upper surface and 
sides of the tongue, and parts of the soft palate and 
pharynx. (See Fig. 66.) Short filaments from the 



THE SPECIAL SENSES 



219 



taste cells protrude through the opening of the bud 
and come in contact with the food tasted. 

1. Does the bud contain any other cells than the taste 
cells? 

2. Do any of the nerves that carry the currents from 
the taste cells to the brain arise outside the taste bud ? 

3. yYipe the tongue dry with a clean cloth and place on 




Fig. 66. Section through a taste bud. A — opening of bud, N — 
nerve, T — taste cell, ep — cells of the mucous membrane. 

it a few grains of sugar. Can you taste the sugar before 
the tongue has again become moist? 

4. Try the same with salt. 

5. Can substances be tasted in the solid form? Or in 
solution only ? 

6. In a spoonful of water dissolve as much sugar as 
you can. With a clean wooden toothpick put a drop of 
this solution on the back part of the tongue. After you 
have perceived the taste, rinse out the mouth and put a 
drop of the solution on the front part of the tongue. Is 
the taste the same in quality and strength at both place-*' 



220 PHYSIOLOGY AND HYGIENE 

7. Try the same experiment with salt, with a drop of 
lemon juice or vinegar, and last with some bitter sub- 
stance, as a very weak solution of quinine. 

8. Is the tip of the tongue more sensitive than the 
back to all tastes? 

9. You might find it interesting to extend these experi- 
ments, comparing the right side of the tongue with the 
left, the edge with the middle of the top, etc. 

10. Mix together two of the substances, as sugar and 
lemon juice, and test with the mixture. Do you taste 
both substances or only one ? Try with different quanti- 
ties of sugar. Does the sweet taste or the sour prevail? 

With practice, taste becomes more discriminat- 
ing. "Tasters" can distinguish in the qualities of 
teas differences so slight as to escape the untrained 
sense. It is probably the brain rather than the 
sense organ that is made more acute by practice. 
To the tongue accustomed to "hot" things like 
red pepper and Worcestershire sauce, mild flavors 
seem insipid and are unappreciated. Therefore, 
strong spices should be used sparingly. 

E. Touch 

In some of the papillae of the skin (Fig. 57) are 
touch corpuscles, in which nerves of touch end. 
When anything comes in contact with the epider- 
mis, the corpuscle is pressed and sends a nerve cur- 
rent to the nerve center — spinal cord or brain. 
Some touch nerves end in cells in the deeper part 
of the epidermis. If the nerve endings are close 



THE SPECIAL SENSES 221 

together, the sense of touch is keen; if they are far 
apart, the sense is dull. 

To test the acuteness of the sense, take a pair of 
dull-pointed drawing compasses and set the points 

one-eighth of an inch apart. Have your neighbor 
hold out his hand without looking at it. Touch the 
palm with one point of the compass and ask him if 
he feel^ one point or two. Then touch with two 
points and ask the same question. If he feels the 
points as two, close the compass gradually as you 
repeat the test till you find the least separation 
that can be felt as tw r o points. Repeat the experi- 
ments for various places on the hand, arm, neck 
and face. 

i. What is the least distance at which the points can 
be felt as two? 

2. What place is most sensitive? 

3. What place do you find least sensitive? 

4. What is the distance between compass points there? 

5. When your hands are very cold are they more or 
less sensitive than when they are warm ? 

F. Temperature 

There are irregular areas all over the body 
which, when touched with a cold object, give us 
the sensation of cold. There are other adjacent 
areas which, when touched with a warm object, 
give the sensation of warmth. Other areas are 
neutral. Since the warm areas and cold areas are 
distinct, they must be supplied by separate nerves, 



222 PHYSIOLOGY AND HYGIENE 

but the nerves of one cannot be distinguished from 
those of the other, and both seem to be like the 
touch nerves that end in epidermal cells. Some 
corpuscles lying deep in the dermis, having nerves 
ending in them, have been supposed to function in 
temperature sensation. 



CHAPTER XIV 

INFECTIOUS DISEASES 

In studying the second chapter, you learned 
what germs are and how they are studied. Now 
you are to learn how the}- attack the body, why 
they cause disease, and how we oppose them. 

Where germs grow. Some disease germs are, in 
the body, strictly limited to certain parts, while 
others are found in several places. Diphtheria 
germs grow in the mucous membrane of the air 
passage, chiefly the pharynx and larynx, and are 
rarely found in any other part of the body. Teta- 
nus (lockjaw) bacteria grow r in wounds, and, 
though they have excellent opportunity to spread 
through the lymph and blood channels, they do not 
do so. The bacillus of tuberculosis grows in any 
part of the body. It is found most frequently in 
the lungs because it comes in with the inhaled air. 
Malaria germs are in the blood, especially in the 
red corpuscles. Pneumococcus in the lung causes 
pneumonia, but it can flourish in other places, as 
in the membranes covering the brain, where it 
causes one form of meningitis. The smallpox germ 

ms to be distributed by the blood through the 
body, but develops pustules in the skin. Typhoid 

223 



224 



PHYSIOLOGY AND HYGIENE 



germs begin their growth in the mucous mem- 
brane of the intestine, but in time spread through- 
out the body. 

How germs do harm. It has been proved that 
many disease-causing microbes produce poisons 
called toxins, and it is thought that all do. Each 
kind of germ has its own toxin, differing from 
every other. Sometimes these toxins are soluble, 
and are therefore taken up by the lymph and 
passed into the general circulation, as with tetanus 
and diphtheria. The insoluble toxins are retained 
within the germ till it dies, when they enter into 
the circulating fluids and spread through the body, 
poisoning the tissues. The virulence of a toxin is 
illustrated by the fact that the toxin produced by 
the tetanus germs growing in one small wound is 
sufficient to produce death. Luckily, not many of 
the toxins are so deadly as this. Many germs 
cause the tissue in which they grow to break down 
rapidly; others produce ulcers that endure for 
months or years. Some germs cause the tissues in 
which they grow to enlarge and harden, forming 
tumors. Still other destructive work of various 
kinds is done either by the germs directly or by 
their products. 

How the body combats germs. It is a fortunate 
thing that not all the germs that get into our bodies 
are able to grow there. In the air of our houses 
and streets are mvriads of microbes, scores of 



INFECTIOUS DISEASES 



22 5 



which we inhale every minute. Manx of these are 
disease germs of various kinds. When the) get into 
the body they meet difficulties. The body does not 
passively suffer the injuries done by disease 
microbes. There are in the blood substances that 
destroy germs, perhaps a separate substance for 
each kind of germ, and that which kills one kind 
has no effect on another. In the blood of some 
people these germicide substances are sufficient to 
kill the disease germs that get into the body. 
These people rarely have infectious diseases. Peo- 
ple in whom the germicidal substances are scanty 
or absent are subject to diseases. 

More important than the germicidal substances, 
in the estimation of many physicians, is the power 
of the colorless blood corpuscles to destroy germs. 
e page 83.) The different kinds of white cor- 
puscles differ from each other in their power of 
ingesting germs, some taking readily certain spe- 

- of bacteria, and others taking other species. 
If the white corpuscles in one's body are active 
germ destroyers, he is less likely to take an infec- 
tious disease, and he recovers more easily if he does 
catch it. A few years ago the discovery was made 
that germs are not at all times equally acceptable 
to the corpuscles. The difference is not in the cor- 
puscle nor in the germ, but in the fluid that sur- 
rounds the germ. There are supposed to be certain 
substances in the blood, called opsonins, that make 



226 PHYSIOLOGY AND HYGIENE 

the germs "taste good" to the corpuscles. If these 
"good tasters" are present the corpuscles take in 
the germs rapidly; if they are not present the cor- 
puscles do little work. To stimulate the body to 
produce "good tasters," injections of serums and 
vaccines are sometimes used. The latter consist 
of dead bacteria of the kind that causes the disease. 
They are injected in quantities of 50,000,000 to 
100,000,000 or more at one time, and the dose may 
be repeated. A serum is obtained from the blood 
of an animal, usually a horse, into whose body has 
been injected the dead or weakened germs or the 
toxin of the disease to be cured. 

A third defense of the body against the injury 
of an infectious disease is antitoxin. This is a 
substance produced in the body to counteract the 
toxin of the disease. Antitoxin combines with the 
toxin and renders it harmless. It is thought not 
to destroy the germs but only their toxins. The 
white corpuscles then take care ,of the germs. Each 
disease has its own specific antitoxin. The pres- 
ence of the toxin in the blood stimulates the pro- 
duction of the antitoxin. If the body responds 
slowly to this stimulus, the toxin may do its fatal 
work before the antitoxin has been produced to 
check it. If the antitoxin is produced quickly and 
abundantly, the toxin is destroyed and the disease 
is soon over. The quick supply of sufficient anti- 
toxin is the requisite for prompt recovery. The 



INFECTIOUS DISEASES 22/ 

solution of this problem is one of the great achieve- 
ments of modern medicine. Diphtheria antitoxin 
may be taken as an example. It is obtained from 
the blood of a horse. Into the body of this animal 
is injected, in measured quantities, diphtheria toxin 
(free from live germs) produced by cultivating the 
bacteria in blood serum in the laboratory. The 
horse's blood produces an antitoxin to counteract 
the toxin. After about a week another larger dose 
of toxin is given the horse and the body produces 
more antitoxin to meet the increased poison. This 
procedure is kept up for several months, till the 
horse's blood is well loaded with antitoxin. Then 
the animal is bled and from the blood antitoxin is 
extracted to be injected into the body of a person 
who has diphtheria. In nearly all cases in which it 
is used early it works a magical cure. It is given, 
also, to children who have been exposed to the 
infection and have not yet become sick, and it 
usually prevents the disease. 

In this section you learn that the body may be 
helped in its warfare against germs by three sub- 
stances — antitoxins, vaccines or dead germs, and 
antibacterial or germicidal substances — introduced 
from without. Some serums have only one func- 
tion, as antitoxin; some may contain a germicidal 
substance and at the same time stimulate the pro- 
duction of "good tasters." The stud}- of this sub- 
ject i- only in its infancy. Every year add- t<> our 



228 PHYSIOLOGY AND HYGIENE 

knowledge of the principles that underlie it and 
to their practical application in remedy and 
prevention. 

Incubation. The time that elapses between ex- 
posure to the infectious disease and the first symp- 
toms of the sickness is called the incubation period. 
During it the germs are growing but have not 
become sufficiently numerous or produced toxin 
enough to cause noticeable effects. If the toxins 
are insoluble they are not set free in the body till 
the germs die and go to pieces, which may be many 
days after they make their incursion. Rabies 
(hydrophobia) has a long incubation, commonly 
more than a month and sometimes considerably 
more than a year. The period of measles is nine 
days, of German measles three weeks, scarlet fever 
two to four days, diphtheria one to five days, 
typhoid fe.ver tw r o weeks, chicken pox ten to fifteen 
days, smallpox nine to fifteen days, and whooping 
cough about two weeks. 

Duration. The germs of a few infectious dis- 
eases, as leprosy and tuberculosis, may continue to 
grow in the body for years, but most diseases run 
their course in a short time. Pneumonia reaches 
its climax in about eight days, typhoid fever runs 
about four weeks. The disease is terminated when 
the opposing forces of the body have overcome the 
germs. If the germs are victorious in the contest, 
their toxin accumulates in sufficient quantity to 



INFECTIOUS DISEASES 



229 



cause death within a certain time. Cholera is some- 
times fatal within a few hours, commonly within a 
day or two. 

Recurrence. Tt is not altogether clear why we 
do not commonly have certain diseases, as mumps, 
measles and smallpox, a second time, while others, 
as pneumonia and scarlet fever, may afflict a person 
several times. Perhaps in some diseases there 
remains in the body an antitoxin or other substance 
that prevents the growth of the germs. It is prob- 
able that every infectious disease is followed by a 
period of immunity lasting, however, in some cases 
only a few days or weeks, while in other cases it 
lasts for months or years. The immunity lasts as 
long as the antibodies, — germicides, antitoxins, or 
whatever they may be, — remain in the body. They 
are in time eliminated with the excretions. The 
products of the germs of one disease sometimes 
prevent the occurrence of a different but allied 
dise; 

Vaccination. The practice of vaccination de- 
pends on the fact last mentioned. It was noticed 
years ago in England that milkmaids who had once 
been infected from certain ^ores on COWS were 
immune to smallpox. Dr. Jenner then introduced 
tile practice of inoculating well people with the 
virus from the diseased cows, giving them the 
pox, that they might be protected from the 
dread disease smallpox. This practice of vaccina- 



230 PHYSIOLOGY AND HYGIENE 

tion was followed in a crude manner for manv 
years. Virus was taken from one person to inocu- 
late another, and occasionally unintended germs 
were in the virus and horrible diseases were com- 
municated. Now the vaccination is performed 
with great care and such disasters very rarely 
occur. A virus carefully prepared is used to inocu- 
late a young cow that is in perfect health. The 
virus "takes" and produces sore spots full of pus. 
This pus, preserved in glass tubes, is the virus 
with which our arms are vaccinated. The exact 
nature of the germ in the virus has never been 
learned. The vaccine grows in our bodies, we have 
this mild disease, which prevents our having small- 
pox. The protection usually lasts several years, 
but the vaccination should be repeated occasionally, 
especially if there is smallpox in the community. 
The vaccination may not take if the virus is not 
fresh, or if the body is in condition to resist its 
growth. In the latter case, the body would prob- 
ably resist smallpox, so we are protected. 

Rabies. Very similar to vaccination for the pre- 
vention of smallpox is the practice of inoculation 
to prevent the development of rabies (hydro- 
phobia). In this case the germs of rabies are cul- 
tivated in the bodies of rabbits, and the germs are 
weakened by drying the brain and spinal cord. 
The inoculation of a bit of this infected substance 
is made only in people who have been bitten by a 



INFECTIOUS DISEASES 



231 



dog or other animal suffering from the disease. 
The weakened germs, introduced in large numbers 
and repeated doses in increasing strength, develop 
more rapidly than the virus of the rabies and pre- 
vent that disease by stimulating the production of 
antibodies. 

A dog that froths at the mouth, acts strangely, 
and has bitten people should, if possible, be con- 
fined instead of immediately killed. If he is care- 
full}- kept a few days, his condition can be studied 
to see whether he has rabies or not. The trouble 
usually proves insignificant and the people bitten 
are freed from apprehension. If the dog is killed 
at once, his victims do not know whether they 
have been inoculated with rabies or not, and 
they either live in dread of the disease or they 
incur the expense of the preventive treatment, 
sometimes going hundreds of miles to a Pasteur 
Institute. If the dog is killed, his head should be 
cut off and sent to an expert, for examination of 
the dog's brain will determine whether he had 
rabies. The Pasteur treatment has recently been 
improved and the appliance^ so perfected that 
the virus used can be sent by mail to any part of 
the country and administered by a local physician. 
The patient can thus live at home and keep on with 
his regular work while taking the treatment. 

Diphtheria. Diphtheria is produced by a bacillus 
which usually appear- first on the tonsils a- a 



2$2 



PHYSIOLOGY AND HYGIENE 



white spot. For a day or two it is difficult to dis- 
tinguish from tonsilitis, therefore cultures on blood 
serum are made from the spot.. If the diphtheria 
bacillus is present, the cultures should show it in a 
few hours. Children with questionable spots in 
their throats are kept in quarantine till the diag- 
nosis is certain. The diphtheria bacilli form a 
membrane which may cover any part of the 
pharynx and spread into the larynx or even the 
trachea. The germs are confined to this surface 
growth, but their soluble toxin is taken up by the 
lymph and distributed through the body. The 
membrane itself may become so large as to stop 
up the air passage and cause suffocation, but the 
passage can sometimes be kept open artificially. 
The toxin is the greatest danger, poisoning the 
nerve centers, especially those that control the 
heart. If the artificial antitoxin is not introduced, 
the toxin is likely to cause death before the body 
can produce a sufficient quantity of antitoxin to 
counteract it. 

Tetanus. Tetanus, or lockjaw, is caused by 
germs which are found in the soil of certain places. 
They can grow in the digestive tract of the horse, 
cow and sheep, and so become scattered in pastures 
and barnyards, spreading the infection among ani- 
mals and providing a supply for a human wound. 
The germs seem to do no injury in the digestive 
tract. Their toxin is probably destroyed by the 



INFECTIOUS DISEASES 



23J 



digestive ferments. But, introduced into the skin 
of the horse or other animal, they may work serious 
or fatal injury. The microbes get into the body 
through wounds that do not bleed much — as rusty 
nail pricks. The toy pistol is especially dangerous, 
since there^are often tetanus germs in the dirt on 
boys' hands, and particles of the exploding cap 
sometimes penetrate the skin, carrying in germs 
with them. Like diphtheria, tetanus is success- 
fully treated with an antitoxin obtained from the 
blood of a horse that has been made immune by 
doses of the toxin. 

Tuberculosis. One-seventh of all the deaths in 
America and Europe are caused by tuberculosis. 
The bacillus which produces the disease is easily 
recognized because it takes a peculiar stain when 
prepared for study under the microscope. It grows 
in almost any part of the body, most often in the 
lungs; then the disease is commonly called con- 
sumption. As it grows it destroys the tissues of 
the body and produces small lumps or tubercles, 
from which it gets its name. The progress of the 
disease varies a great deal in different persons; 
some live many years without seeming to get much 
worse, others succumb within a few months. Many 
people recover from the disease without difficulty. 
Even when seriously sick, the sufferer usually feels 
so hopeful of getting well that he neglects to take 
the means necessary to a cure. Tuberculosis is 



234 PHYSIOLOGY AND HYGIENE 

one of the diseases successfully treated with a 
serum. But the most important treatment is 
plenty of nourishing food and fresh air. A climate 
in which the patient can remain out of doors day 
and night, the year round, is often sought; and 
even in cold climates the patients sleep out of doors, 
warmly wrapped up. 

Tuberculous people are everywhere, in houses, 
shops and streets. The germs growing in their 
lungs are thrown out in expectoration. They dry 
up and blow about in the dust. We inhale them 
and are so exposed almost daily to the infection. 
If people suffering from the disease would be care- 
ful of their expectorations, never spitting on floors 
or streets, we should be much less exposed to the 
germs. 

This most fatal of all diseases, well known as an 
infectious disease, is only recently recognized as 
such by law. People having measles, smallpox, or 
scarlet fever are not allowed to spread the infec- 
tion, but there are in most states no laws ade- 
quately guarding against the spread of tuberculosis. 

Many people have thought the disease to be 
hereditary, and some color is given to the supposi- 
tion by the fact that tuberculous parents often have 
tuberculous children and grandchildren. The chil- 
dren do not usually inherit the disease ; but if par- 
ents are diseased the children are usually weak, 
and being daily exposed to the bacilli, often con- 



INFECTIOUS DISEASES 235 

tract the disease. Moreover, some people are 
especially susceptible to the disease, and this sus- 
ceptibility is likely to run in the family. Many 
people advocate a law forbidding the marriage of 
men and women suffering from tuberculosis. A 
conscientious person who has the disease and who 
understands its power to injure the lives of others 
will not marry, and will exercise every care to pre- 
vent the spread of the germs in any way. 

Other animals than man are subject to tuber- 
culosis. It is quickly fatal to monkeys. Cows may 
have the disease a long time without its being 
noticed, and people have feared that their milk 
might spread the disease among men. Humans do 
contract bovine tuberculosis, but whether the dis- 
ease may be transmitted by the milk has been much 
disputed. Cities that are most careful of their milk 
supply are requiring the animals that provide it to 
be free from tuberculosis. 

This plague is most rampant in the crowded city 
tenements occupied by factory workers. Workers 
at confined and dusty trades are especially sus- 
ceptible. The air they breathe is laden with germs 
and poisonous exhalations, their chests are cramped 
and weak, their wage is so small that they are often 
insufficiently fed. The feeble fall easy victims to 
this plague. The tenement sleeping rooms are 
dark, crowded and ill-ventilated. The germs of the 
disease are killed by sunshine, but in the dark and 



236 PHYSIOLOGY AND HYGIENE 

dirty nooks of the tenement they live many months, 
bringing death to old and young. 

The disease is preventable, and if we lived ration- 
ally, it would almost disappear in a generation. 
We should have to live in light, clean, airy dwell- 
ings, spend a good deal of time out of doors, and 
have plenty of wholesome food. 

Medicines. Aside from the antitoxins and bac- 
tericidal serums, there &re only a few drugs known ■ 
that will cure any infectious disease. The attending 
physician may give medicines to accomplish various 
desired ends — to move the bowels, to stimulate the 
heart, or to act as a sedative ; but the cure, the 
destruction of the germs, must come from the body 
itself. The emulsions given for tuberculosis are 
fat foods, not drugs. When you find anyone adver- 
tising to cure, by a process or drug known to him 
alone, any disease whatever, you may be sure he is 
untrustworthy. The germs of an infectious disease 
can easily be killed by antiseptics, but so can the 
body. The problem is to find something that will 
poison the germs without harming their host. A 
few drugs have been discovered that can be tol- 
erated by the body in sufficient quantity to destroy 
the germs. Quinine, given for malaria, is one of 
these. Germs whose growth is limited to the sur- 
face of the body can be reached by antiseptics. 
Many individual germs in a colony causing diph- 
theria, tonsilitis, or catarrh can be killed by an anti- 



INFECTIOUS DISEASES 237 

septic spray, but some of the germs penetrate the 
mucous membrane so deeply that they could be 
readied only by those poisons which would destroy 
the membrane. Germs on the skin, however, can 
sometimes be completely destroyed by an antisep- 
tic. Ringworm, caused by a mould-like vegetable 
growth, can be completely cured by one or tw T o 
applications of iodine, if the parasite has not 
become intrenched in the deep hair follicles of the 
scalp. 

This chapter on infectious diseases has not 
accomplished its purpose unless it has helped you 
see that the cure of any disease lies mostly in the 
body itself. Sometimes the defenses of the body 
can be augmented by serums from other animals, 
and a few drugs can be used to advantage; but we 
are mainly dependent on the work of our own cells. 
Careful nursing and dieting is valuable in conserv- 
ing the strength of the sick. Hygienic living every 
day is the best assurance of recovery from sickness. 
Those whose bodies are weakened by dissipation, 
overwork, bad air or insufficient food suffer most, 
from infectious diseases. 



CHAPTER XV 
DISEASE, DRUGS, AND DOCTORS 

What disease is. We have learned in the fore- 
going chapters that all the cells of the body have 
certain life activities, such as motion, assimilation 
of food, oxidation, growth and repair. Besides 
these general activities each tissue has its special 
functions; some secrete, some contract, some send 
nerve currents and some store food. If the cells 
are performing their normal activities we are in 
health. Inability of any cells or organs to perform 
their functions is disease. 

Cause of disease. Diseases are due to causes 
some of which are well understood and some are 
still unknown. It is very clear that if a part of the 
body never fully develops, as a shriveled arm or 
leg, it cannot do its normal work. An overgrowth 
or faulty structure may likewise interfere with the 
activities of parts of the body. Also an accident 
that destroys a portion of an organ impairs the 
working of that organ. Parasites, whether biting 
or crawling into the skin or living in the intestine 
or other parts of the body, sometirhes interfere with 
the working of the organs they infest. But most 
diseases are caused by defects less conspicuous. 

238 



DISEASE, DRUGS, AND DOCTORS 239 

Individual cells may be affected so that their func- 
tion is impaired in ways revealed only by the micro- 
scope, or sometimes not revealed by any known 
means. Yet the organ of which the cells arc a 
part may not show any noticeable imperfection. 
Many poisons have such subtle effects. Most of 
the common diseases are caused by germs, which 
produce poisons that either destroy tissues or so 
affect the cells as to prevent their normal activities. 
The treatment of a disease. Disease must be 
treated according to the nature of the defect in the 
cells and the cause of the injury. No disease can 
be cured while the thing that produces it is still 
present and working its harm. This book can do 
you no greater good than to teach you to treat the 
body rationally, in sickness as well as in health. 
All superstitions and old household remedies must 
be called in question. When put to the test of 
reason and science most of them fail and must be 
discarded. Xo common report that a certain rem- 
edy or course of treatment has cured a patient is 
worth much consideration. Common reporters are 
not qualified to judge. A remedy or treatment 
should be accepted only when, by repeated 
trials, in hundreds of carefully studied cases, it 
has proved to the most thorough scientific ob- 
servers its beneficial effects. Make a list of as 
many remedies for various diseases as you can 
learn through your neighbors, and see how many 



240 



PHYSIOLOGY AND HYGIENE 



you can find a rational ground for using. Try to 
find out in what way each is supposed to remedy 
the particular defect of the disease. Of course a 
remedy is not to be declared worthless just because 
a school boy cannot see how it may be valuable; 
but if you can find no one able to give a reasonable 
ground for its use, its value is to be strongly 
doubted. A lively skepticism is a good attitude of 
mind for a student. 

The cure of disease. Diseases are cured by re- 
moving their causes. If a disease is caused by a 
parasite, the parasite must be killed or driven away. 
When the parasite is on the skin (as lice, the itch 
mite, ringworm) kerosene, iodine or poisonous 
ointment can be applied directly and the offender 
destroyed. Worms in the intestine can be de- 
stroyed and expelled by the use of certain poisonous 
drugs. The difficulty about killing the parasites of 
most germ diseases is that the drugs that destroy 
the germs would also kill the patient. There are 
only a few drugs known that can be taken in doses 
sufficient to destroy the germs without harming 
the patient. Among these are quinine, which kills 
the malaria germs; and a compound of arsenic, 
which destroys the germs of syphilis and of sleep- 
ing sickness. Calomel and salol kill some germs 
in the intestinal tract. 

Since the white blood corpuscles destroy germs, 
anything that increases their action will help cure 



DISEASE, DRUGS, AND DOCTORS 241 

the disease. Vaccines or bacterines (see page 220 ) 
are used for this purpose. Germs injure the body 
by means of the toxins they produce. If the toxins 
could be rendered harmless, the germs would soon 
be destroyed by the white corpuscles. Antitoxin 
(see page 226) is used for this purpose in diphtheria 
and tetanus. 

Deficiency in organs. Sometimes, although the 
cause of the failure of certain organs to perform 
their functions is not understood, the organs can 
be brought to do their work bv certain treatment. 
For example, constipation (which means deficient 
secretion in the colonic mucous membrane and fail- 
ure of the intestinal muscles to expel the feces) is 
relieved by medicines that stimulate the muscles 
and glands of the intestine. Massage of the abdo- 
men also stimulates the organs to activity and will 
often relieve the trouble. If the heart is doing its 
work poorly, there are stimulating drugs that whip 
it up and make it beat more vigorously. If the 
digestive glands fail to produce sufficient digestive 
fluids, the deficiency can be made up by taking fer- 
ments extracted from the digestive organs of 
slaughtered animals. A failure of the thyroid gland 
can be likewise compensated by the use of an 
extract from the thyroid gland of a sheep. 

Malformations. When the failure of certain 
organs to do their work is caused by interfering 
growths, as adenoids blocking up the respiratory 



242 PHYSIOLOGY AND HYGIENE 

passage, a surgical operation will remove the ob- 
struction. Crooked limbs, cross eyes, cataract, 
pressure on the brain, tumors and many other 
structural defects can often be completely cured by 
the skill of the surgeon. 

Indirect effects. Drugs and applications are 
much used to produce results that are not cures. 
The immediate relief of pain does not work a cure, 
yet it is often an advantage. It is sometimes 
accomplished by drugs that benumb the nerves, 
sometimes by hot applications, by ice, by elec- 
tricity, or by counter-irritants. Tissues that are 
injured may be able to recover without any assist- 
ance if they are kept quiet. Certain drugs may be 
used to check the activity of these or neighboring 
tissues and so bring the needed rest. If some organ 
is congested, the unusual blood pressure may be 
relieved by drawing the blood away to some other 
place, by means of a counter-irritant or a blister. 
On this principle a plaster is applied to the skin 
to relieve a pain in the deeper tissues; the feet are 
put in hot water to relieve headache. 

No attempt is made in this chapter to give all the 
purposes for which drugs or methods of treatment 
are used. We are merely trying to show that there 
is a rational aim in every proper procedure. Some 
treatments are intended to cure the disease directly, 
others are to relieve harmful symptoms, others to 
establish conditions under which the bodv can work 



DISEASE, DRUGS, AND DOCTORS 243 

its own cure. Unless the treatment of the disease 
is rational, it is just as likely to be harmful as bene- 
ficial. The obligation we feel to k4 do something" 
for a sick person drives us to all sorts of ridiculous 
actions. We should do only what we have a good 
reason for doing, not whatever may be recom- 
mended by those who know nothing of the func- 
tions of the organs or of the physiological effects 
of drugs or of methods of treatment. 

Physicians. The skilled physician prepares him- 
self for the rational treatment of disease bv years 
of study. It is our duty to put a sick person into 
the hands of a physician and to obey his directions 
scrupulously because he knows better than any one 
else what should be done. But w r e should never 
forget that there are doctors and doctors. Though 
most physicians of good repute do the best they 
can for their patients, there are thousands of incom- 
petent practitioners and thousands of charlatans 
who aim to get their patient's money by fair means 
or by foul. It behooves one to select his physician 
with the greatest care. The doctor who is most 
genial or most active in society or runs about with 
the most appearance of business may not be the 
most competent scientist. Put your trust in the 
physician whom his fellow practitioners trust. 
They usually know r which of their brethren have 
had thorough scientific training and carry level 
head-. There is one "doctor" always to be avoided 



244 PHYSIOLOGY AND HYGIENE 

— he who professes to be able to cure what others 
cannot, who advertises himself, guarantees a sure 
cure or money back. The ethics of the profession 
forbids advertising, and all reputable practitioners 
observe the prohibition. No physician has any pri- 
vate drug or method unknown to the others. The 
ethics of the profession makes it obligatory on 
everyone to communicate to the others anything he 
may learn that will promote the health of mankind. 
The scientific physician is of no "school"; that 
is, he does not limit his treatment by any precon- 
ceived theory of how diseases can be cured. He 
uses the methods that have stood the test of experi- 
ence, and is ever open to any new method that can 
stand the severe trial put upon it. The great ad- 
vancements in the treatment of disease made 
within the last few years have all been made by 
such scientific physicians. Knowing that the regu- 
lar physicians are eager to adopt any new method 
of treatment just as soon as a fair trial has proved 
it valuable, we use very poor judgment when we 
run after a fakir who claims to work cures by some 
new or private discovery. The fact is that every 
"quack" produces a great number of "cures" and 
gets plenty of testimonials of his skill. Most dis- 
eases usually get well if they are not treated too 
badly. . The doctor in attendance gets the credit, 
whether his treatment did good or harm. Many 
cases of disease depend on the state of the mind, 



DISEASE, DRUGS, AND DOCTORS 245 

and are cured by abolishing worry and fear, by 
establishing hygienic habits of eating, working and 
resting, and by leading the patient to think he is 
getting well. Such cases can be cured by faith 
healers, and quacks, and doctors of any school as 
well as by regular physicians. Furthermore, many 
testimonials are bald falsehoods or statements 
made by people too ignorant of the subject to know 
whether or not they are true. Even the best 
trained and most clear thinking physicians are none 
too able to meet the problem of sickness, and we 
are grievously at fault if we allow an incompetent 
pretender to take the place of the skilled scientist. 
Patent medicines. Patent medicines are mix- 
tures of drugs designed to be used, without the 
advice of a physician, by people who are, or imagine 
themselves to be sick. Such preparations are often 
supposed to be secret and to have virtues not pos- 
sessed by the drugs used by regular physicians. 
The truth is that the constituents of these medi- 
cines are well known to the medical fraternity and 
many of them are in common use. The patent 
medicines may now and then produce good results, 
but they are harmful in many cases. People who 
use them are incompetent to apply them just when 
they might be useful and to judge of their effects, 
Many of them contain alcohol and other harmful 
drugs. The supposed beneficial effect i^ often only 
the exhilaration produced by the alcohol. They are 



246 PHYSIOLOGY AND HYGIENE 

almost never used rationally; that is, with an un- 
derstanding of the nature of the disease to be cured 
and of the power of the drug to accomplish the 
desired result. The habit of using drugs is exceed- 
ingly vicious. No one who appreciates the differ- 
ence between the scientific treatment of disease and 
quackery will have anything to do with patent 
medicines. 

In the same class with patent medicines are all 
sorts of patent and traditional appliances to be used 
without the physician's advice, such as magnetic 
belts, amber beads, charms and curative jewelry. 
They are usually harmless, but utterly useless and 
silly. They encourage superstition, and are very 
objectionable when they take the place of treat- 
ment that might be helpful. 

Prevention. More important than the cure of 
diseases is their prevention. We spend many times 
as much money in treating diseases as in checking 
their spread. The more we spend in preventing, 
the less we should need to spend in cure. There- 
fore, it would be financially more economical for 
us to double or triple the sums spent in preventing 
disease, and thereby reduce many fold the cost of 
treatment, as well as lessen the suffering and death 
from sickness. The work of prevention may be 
classed under two heads, — personal hygiene and 
sanitation. Matters of personal hygiene are such 
as each individual can attend to with reference to 



DISEASE, DRUGS, AND DOCTORS 247 

his own body. They have been discussed in each 
chapter of this book. Sanitation is concerned with 
matters that are generally beyond the control of 
individuals and must come under the care of the 
community organization. They include water sup- 
ply, sewage, pure food, quarantine, destruction of 
germs, etc. They are discussed in the next chapter. 



CHAPTER XVI 

SANITATION 

The two chapters immediately preceding this 
treated infectious diseases from the standpoint of 
the individual case of sickness. This chapter dis- 
cusses the subject from the social standpoint. We 
are here concerned with the fight against the spread 
of infectious diseases. We must learn how diseases 
are spread before we can understand the method 
of checking their communication. The first prob- 
lem is divided into two parts: 

(A) How Disease Germs Escape from the Sick 

Digestive tract. In diseases of the digestive 
tract, the germs grow in large numbers in the intes- 
tine and are consequently discharged by the million 
with the excreta. The germs may lurk in some 
part of the digestive system, as in the gall bladder, 
and may contaminate the bowel discharges months 
after the patient has recovered from the disease. 
Some germs that are distributed by the blood are 
very likely to be excreted by the kidneys and 
discharged with the urine. The germs of local 
infections of the urinary organs are also thus 
discharged. 

248 



SANITATION 249 

Respiratory passages. Germs that infest the res- 
pirator}' tract are easily discharged from the nose 
and mouth, not in ordinary breathing, but in cough- 
ing-, sneezing, spitting and blowing the nose. It 
has been found that after a sneeze or cough germs 
may remain floating in the air many minutes, and 
extending several feet away — practically contam- 
inating all the air of a small room. It has been 
estimated that seven billion tuberculosis germs may 
be expectorated by a consumptive in one day. You 
see the reasonableness of an ordinance forbidding 
spitting on floors and sidewalks. The handkerchief 
of a person suffering from any respiratory infec- 
tion, even such a mild form as a cold, should be 
carefully handled that the germs may not be spread 
about on the hands or clothing. 

Skin. Diseases which have skin eruptions dis- 
seminate the germs from the pustules or scales of 
the skin. Germs of such diseases are pretty sure 
to get on the clothing. They brush off and blow 
off from the skin and are easily spread. There is 
no security near one sick with any of these diseases, 
therefore the need of scrupulous quarantine. 

A few diseases are often communicated by the 
bite of insects. A mosquito sucks the blood of a 
person sick of malaria <>r of yellow fever; some 
time later the same insect, biting a healthy person, 
injects the germs into him and so spreads the dis- 
ease. Fleas in like manner communicate the 



250 



PHYSIOLOGY AND HYGIENE 



bubonic plague, and the tse-tse fly in Africa the 
sleeping sickness. 

(B) How Germs Enter the Body 

Respiratory passages. Since germs are so easily 
thrown off into the air by the sick, or after being 
dried are blown about in dust, they find their most 
common entrance to the body in the respiratory 
passages. You have already learned how well 
adapted the respiratory tract is to keep germs from 
lodging in the lung — the crooked passage with 
moist walls which catch the germs, the cilia which 
sweep them back to the entrance. Though the 
great majority of germs are thus removed, a num- 
ber, large enough to maintain a foothold and pro- 
duce disease, often get into the air sacks, where 
they can grow more easily than on the ciliated 
membrane. Some germs do, however, lodge and 
grow in the bronchial tubes and trachea. The 
spongy tonsils and folds of the nose offer a place 
for the lodgment of germs and are frequently the 
seat of infection. The upper part of the nose cavity 
lies very close to the floor of the brain, and the 
nerves of smell are an avenue along which, it is 
thought, the germs of meningitis sometimes pene- 
trate. We probably always harbor several kinds 
of germs in the nasal passages, some of which are 
capable of producing disease. These are lying in 
wait, ready to develop when the body becomes unfit 



SANITATION 25 1 

to resist them, through exposure, fatigue, lack of 
nourishment, or illness. 

The digestive tract. Another easy avenue of 
entrance for disease germs is the digestive tract. 
The warm, moist mouth, with particles of food 
between the teeth, offers suitable conditions for 
microbe growth. About thirty kinds of germs have 
been found in the mouth, many of them capable 
of producing disease. A few kinds of harmless 
germs may grow in the healthy stomach, but the 
hydrochloric acid of the gastric juice is an anti- 
septic and most germs do not flourish where the 
juice is normal. Stomach infection usually means 
defective gastric juice. In the intestines, especially 
the latter part of the small intestine, and the whole 
of the large intestine, the conditions seem almost 
to invite germ growth. Besides the germs of 
typhoid, cholera, diarrhea and dysentery, which 
infest the intestinal tract, a number of others prob- 
ably gain entrance here and spread through the 
body. The retention of the feces in the colon gives 
opportunity for the growth of germs of decay, 
whose toxins are absorbed, producing headache and 
fever. The bowels should be emptied at least once 
a day. 

sides the microscopic parasites, there are sev- 
eral \vorm> that infest the digestive tract. Most 
of these are taken in with the food, and spend their 
life in the intestine, producing discomfort or severe 



252 PHYSIOLOGY AND HYGIENE 

illness. Trichina penetrates the walls of the tract 
and spreads through the body, often with fatal 
results. The hookworm, which has produced such 
havoc in the West Indies and the Southern States, 
gains entrance to the body through the bare feet. 
In time it comes to the intestine, where thousands 
may hang fastened by little hooks. .Well-known 
drugs will kill and remove most worms. 

The skin. Some kinds of germs make their en- 
trance to the body through breaks in the skin, as 
those of tetanus, rabies and blood poisoning. Ma- 
laria, bubonic plague, yellow fever and sleeping 
sickness are introduced by biting insects. Some 
pus-forming germs work down into the oil glands 
and a few into the sweat glands, producing pimples, 
boils and carbuncles. There are a few kinds of 
surface parasites, as ringworm, that grow in the 
epidermis, hair follicle and glands, and never 
penetrate below the skin. Wounds offer an easy 
avenue to a variety of germs that grow in the 
blood, but, so long as the skin is unbroken, it pre- 
sents an almost perfect barrier to the ingress of the 
germs of severe disease. (See page 188.) It is 
important, then, that we avoid even trifling 
wounds, and that we keep cuts and scratches cov- 
ered and clean. It is well to apply tincture of 
iodine or a solution of potassium permanganate or 
other effective antiseptics to even slight wounds. 
Boracic acid is too mild to be of much value in 



SANITATION 253 

such uses, and the frequently employed hydrogen 
peroxide is inefficient and decidedly objectionable 

in fresh wounds. 

Means of Prevention 

Destroy germs. A bright light, sunshine, or a 
very strong artificial light kills most germs in a 
few hours. It is the dark tenements and not the 
well-lighted homes that harbor tuberculosis and 
other respiratory diseases. Desert air is whole- 
some, free from disease and decay, because nearly 
all the hours of daylight are hours of sunshine. 
Drying is also a potent factor in the destruction 
of germs. Many microbes produce spores that can 
withstand considerable drying, while others suc- 
cumb easily. The most thorough means of killing 
germs is by heat. Ordinary cold temperatures do 
not kill germs: but no germs, not even spores, can 
long endure a boiling temperature. A dry heat 
above the boiling point is the best destroyer, 
though boiling water or boiling hot steam is effect- 
ive. Boiling heat should be applied for about an 
hour; a higher temperature requires less time. 
Many poisons (antiseptics and disinfectants) are 
used to kill germs. Different poisons are suited to 
different u^e^. Mercury bichloride (corrosive sub- 
limate 1 ha^> been a favorite for washing surgeons' 
hand-: carbolic acid and lysol for sterilizing thread 
and instruments. Alcohol, boracic acid, formalin 



254 PHYSIOLOGY AND HYGIENE 

and lime are also common substances used for kill- 
ing germs. Care must be taken that the poison 
actually comes in contact with the microbes. 

Disinfection. The discharges from the mouth, 
nose, kidneys and bowels can be disinfected as an 
important means of preventing the spread of infec- 
tious diseases. Quick lime is a cheap and effective 
agent for disinfecting dry privies and waterclosets. 
It loses its strength by air-slacking, so it should be 
used fresh, either dry or dissolved in water (milk 
of lime). Lime destroys cloth and leather, and is 
used only on that which is to be thrown away. 
Burning is the best means of destroying sputum. 
Lysol in the sputum cup is a good disinfectant. 
Handkerchiefs containing infectious discharges 
should be thoroughly soaked in an antiseptic or 
boiled, before going to a common laundry. Wash 
clothing can be disinfected by boiling, but other 
fabrics can be more conveniently treated by 
fumigation. 

Fumigation. Destroying germs by fumes or 
poisonous vapors is fumigation. Rooms are usually 
fumigated, as are also fabrics that will not endure 
washing. Formalin and burning sulphur are the 
common agents employed. The room should be 
tightly closed, the cracks of the windows and 
doors covered with strips of paper or adhesive 
plaster. The beds should be opened and the clothes 
spread out loosely, that the fumes may penetrate 



SANITATION 



255 



to every part. Formalin may be sprinkled on a 
sheet to evaporate, or, better, introduced through 
the keyhole as a vapor. The sulphur is lighted 
after the arrangements are finished, and the oper- 
ator quickly leaves the room and makes the door 
cracks tight. The room should remain closed sev- 
eral hours. Thorough fumigation destroys all dis- 
ease germs and most vermin, but formalin fumes 
do not kill bedbugs. 

Quarantine. It is desirable that people suffering 
from most infectious diseases be kept away from 
other persons. We maintain a strict quarantine in 
cases of diphtheria, smallpox, scarlet fever and 
some other diseases. We are coming to be more 
careful of pneumonia and meningitis. The germs 
of influenza (grippe) and colds are already so wide- 
spread that practically everyone is now exposed to 
them. We have to resist them, not keep them 
away from us. Moreover, these diseases are 
usually so light that sufferers from them can attend 
to their business and would resent the loss of 
income that would result from quarantining them. 
When we suffer from these diseases that are not 
subject to quarantine, we should be especially care- 
ful not to spread the germs by coughing or expec- 
torating in public places; and in such diseases as 
cholera and typhoid we should take the precaution 
of disinfecting the excretions. A little care may 
save many lives. 



256 PHYSIOLOGY AND HYGIENE 

Biting insects. Cases of diseases of which the 
germs are carried by insects should be kept away 
from insects as much as possible. Patients suffer- 
ing from malaria and yellow fever should be kept 
behind mosquito-tight screens. In Africa, the 
tse-tse fly infests the low lands along the water 
courses. If the people could remain in the upland, 
they would be free from the sleeping sickness. The 
extermination of obnoxious insects is an important 
means of safety. The bubonic plague is carried by 
a flea which infests rats and squirrels. Free a city 
from these animals, and you check the spread of 
the plague. The United States government and 
the local authorities of San Francisco combined 
their forces to that end, when the plague was 
recently introduced into that city. Scientists may 
well turn rat-catchers when by so doing they can 
save thousands of lives and millions of dollars, as 
was done in the successful campaign in San 
Francisco. 

Mosquitoes lay their eggs on the water. The 
young (called wigglers) live in the water, coming 
to the surface to breathe — living most of the time 
at the surface with the breathing pore open to the 
air. When grown to full size, the wigglers go into 
a resting stage, during which time the body is 
transformed into the winged insect. Then the skin 
cracks open, the mosquito draws himself out of the 
empty shell floating at the surface of the water and 



SANITATION 



257 



flies away. Since the wigglers cannot remain away 
from the surface, the}' are easily destroyed by a 
film of oil on the water. An exceedingly thin film 
of oil is sufficient to get into their breathing pore 
and cause death. The warfare against mosquitoes 
consists in draining swamps, filling mudholes, and 
sprinkling with cheap oil the standing water that 
cannot be drained. In stamping out yellow fever 
in Xew Orleans, it was found necessary for sanitary 
inspectors to go from house to house, emptying the 
receptacles for waste water, and compelling people 
either to screen their barrels of water, or to put in 
enough oil to cover the surface. Fine-meshed mos- 
quito-bar, protecting both sick and well, is not only 
a convenience but also a sanitary precaution. 

Food. A large part of the infectious sickness 
which we suffer could be prevented by greater care 
of the food. Thorough cooking sterilizes food, but 
"there's many a slip 'twixt cup and lip." After the 
food leaves the stove, there is chance for it to 
become contaminated before it reaches the mouth. 
The dishes in which it is served may have been 
washed in impure water, the cook sometimes has 
an infectious disease, but the worst of all defilers 
are the flies. If the flies get no chance to pick up 

'tns, they are merely filthy and annoying; but 
when they can get to the germs they bring disease 
with them. Raw vegetables — celery, radish, let- 
tuce, cress and the like — may brine us the ererms 



258 PHYSIOLOGY AND HYGIENE 

from sewage used to fertilize the soil or from 
handling in the market. 

Milk is easily contaminated, and is such good 
food for the germs that they increase rapidly in it. 
It is often so filled with germs as to be unfit for 
human food. Infants especially, whose chief food 
is milk and whose digestive tract is not accustomed 
to the fermentive and putrifying bacteria, suffer 
from bad milk. If milk is properly handled, the 
number of germs of souring and decay can be kept 
within a harmless limit, and the microbes of infec- 
tious diseases altogether excluded. Milk should be 
cooled within a few minutes after it is drawn from 
the cow, and kept cool until it is used. Of course 
cleanliness must be maintained always; bottling 
helps in this. 

If we are not careful, we are likely to take in with 
our food, besides the germs of infectious diseases, 
the poisons of decay. Every large city has its corps 
of sanitary inspectors, one of whose duties is to 
go through the markets and see that no spoiled 
meat or decayed fruit is sold. The germs of decay 
produce poisons (called ptomaines) which may not 
be perceived by the buyer, but which may cause 
sickness and death. The worst ptomaines of meat 
are those produced by germs growing in the bodies 
of sick animals. It is best to exclude from the 
market the flesh of all sick animals. 

Flies. One of the commonest germ-carriers is 



SANITATION 



259 



the house fly. It eats germs and gets its feet cov- 
ered with them. Then it visits the table, shaking 
the microbes o\i its feet and depositing in its specks 

the microbes that pass undigested through its intes- 
tines. Hundreds of germs can be left in this way 
by a single fly. The dining room and the kitchen 
should always be screened against dies. These 
pests should be scrupulously excluded from the sick 
room, also, lest they pick up the germs and carry 
them to other rooms and other houses. We should 
above all take pains to prevent the breeding of 
these insects. The fly lays her eggs in all sorts of 
filthy places — barnyard manure, garbage, dead rats, 
bones or scraps the clog leaves, etc. It takes about 
a week for the eggs to hatch and grow into mature 
insects. Garbage cans should be shut tight to 
exclude flies, but if they are emptied and thor- 
oughly cleaned even once a week, they cannot 
breed Hies. A little pains in keeping the premises 
free from filth}- litter, and keeping the manure in a 
closed box and frequently carted away, will give 
relief f r< >m the fly pe 

Drinking water. The most common carrier of 
disease germs that infest the intestines of adults is 
drinking water. Water supplies are easily contam- 
inated with sewage, and sewage is pretty sure t<> 
contain the germs of intestinal diseases. For small 
cities, artesian wells afford a safe supply of water, 
but such wells are possible only in certain districts. 



26o PHYSIOLOGY AND HYGIENE 

They cannot supply water enough for a large city. 
The problem of water supply for cities is too great 
for discussion here. The individual is dependent on 
the community supply, but if this is bad he can 
protect himself by boiling the water or by using 
distilled or spring water privately supplied. In the 
country each family usually has its own well, which 
can be made to supply wholesome water, but often 
is a source of infection. The well curb should stand 
a little higher than the surrounding ground and be 
thoroughly cemented up, that no rain water can 
run in from the surface and no rats or other vermin 
gain entrance. Care should be taken in the loca- 
tion of the well that it is so situated that the water 
which seeps in to supply it does not come from 
barnyard, privy, or any impure source. You can 
not always tell by the taste or smell whether water 
is wholesome. There may be hundreds of germs 
in a glass of water that is clear and odorless. 

Clean air. Clean air is more necessary to health- 
ful living than we commonly think. Dust and 
germs are usually mixed in the dirty air of our 
streets and buildings. Rough boards covered by a 
nailed-down carpet make a very unhygienic floor. 
The floors should be smooth and tight, so dressed 
that they can be conveniently wiped with a damp 
or oily cloth that will pick up all dust. Rugs that 
can be removed to be dusted are the only suitable 
carpets. The vacuum cleaning process is to be 



SANITATION 261 

commended, because it removes all the dust it dis- 
turbs; a broom Tills the air with tiny particles from 
the floor, which get into the cupboards, penetrate 
the draperies and settle on the furniture. Street- 
sprinkling makes the air not simply more pleasant 
hut also more hygienic. The oil dressings for 
streets are to be particularly commended; they 
hold the dust so well that the}' need no sprinkler 
to make them muddy several times a day. City- 
dwellers, filling their lungs with smoke every day, 
seem to think that clean air is not possible in a 
large community. Smoke is harmful to the lungs, 
and a polluted atmosphere is not necessary to 
either a commercial or a manufacturing center. 
When our social conscience is more fully aroused, 
we shall cease defiling the city air with smoke and 
unwholesome odors. 

Light. One of the most important subjects of 
public sanitation is light. We have seen that it is a 
potent germ destroyer. The inadequate light of 
tenements and factories is responsible for the ruin 
of many eyes, and the resulting deficiency of work- 
er-. In our own homes we can do something in 
the cause of better light by throwing up the shades. 
Better bleach the wall paper and furnishings than 
-hut out the wholesome sunshine. We ought to 
build houses that will admit abundant light, fit them 
with furnishings tolerant of light, and keep them 
so clean that we shall not be ashamed to let in the 



262 PHYSIOLOGY AND HYGIENE 

sunshine. The worst offenders against light are 
the tenements of the poor in large cities. Space is 
so valuable that rooms are small, stairs and pas- 
sages are dark and narrow, and the open areas for 
light and air altogether too insufficient. The 
profits that come to the landlord from crowded 
tenements seem too great for him to resist. The 
remedy is in the strict enforcement of building 
ordinances w r hich provide for plenty of light and 
air in every tenement room. 

Noise. It seems to those who live in a quiet 
world that noise has nothing to do with health. 
To those, however, who live in a city full of noises 
and who suffer from nervous disorders, the sooth- 
ing influence of quiet is appreciated. No one can 
tell how much the nervous equilibrium of well peo- 
ple is disturbed by noise. We ought to conserve 
all our energy for the needs of life, and to this end 
shut out unnecessary noises and nerve-racking 
offenses. The "zone of quiet" established around 
hospitals for their protection against disturbances 
might well be extended. We ought especially to 
guard our sleeping hours, that our quiet slumbers 
may bring the strength we need for the day's 
labors. 





INDEX 


Absinth, 147. 




Carbohydrates, 130. 


Absorption, 182. 




Carbolic acid, 29, 253. 


Adenoids, ill. 




Carbon dioxide. 17. 10. 38, ro8, 


Adrenalin. 100. 




120. 


Alcohol. 43, 61, 77. 107, 


1 28, 


Carbuncle, 31. 


140. 144. 170. 181, 196. 


[98. 


Cartilage, 44. 


Anastom 




Cell, 12. 


Anatomy, 1 1. 




Cell division. 16. 


Antiseptic. 29, 236, 253. 




Cell forms, 14. 


Antitoxin. 226. 




Cerebellum, 68-70. 


Appetite. 137. 




Cerebrum. 68-70. 


Aqueous humor, 205. 




Champagne. 145. 


Arteries. 85. 




Chew, 161. 


Assimilation, 16. 




Chloral, 153. 


Astigmatism, 208. 




Chocolate, 144. 


Auricle. 103. 




Choroid coat, 204. 


Automatic action, 67. 




Chyle, 183. 


Bacteria, 24. 223. 




Chyme, 177. 


Racterine, 226. 




Cilia, 116. 


Bath, 193. 




Circulation, 81. 


Biceps, 50. S3- 




Clot, 84. 


Bile, 178, 185. 




Clothing, 195. 


Blindness, 210. 




Coagulation, 84. 


Blood. Si. 




Cocaine, 141. 153. 


Boils. 31. 




Cochlea, 215. 


Bones, ^2. 




Cocoa, 144. 


facial. 38. 




Codeine. 1 ?2. 


cic acid, 20. 252, 253. 




Coffee, 143. 


Borax. _ 




Cognac. 147. 


Brain, 68-70. 




Cold. 124. 


Brandy, 147. 




Condiment. 130. 


Breathing. 1 17. 




Conjunctiva, 


dust in. 1 [6, 124. 125. 




C inservation of energy, 18. 


Brewed liquor. 145. 




Constipation, 175. 


Bronchial tubes, n 2. 1 14. 




Consumption, 223, 233. 






Cooking, 173. 


■ »n. 46. 




< >rns, 4^>. 


in, 143. 




( a >rnea, 204. 


38. 




< ronary, U 


Canaliculi, 




rpus collosum, 68, 70. 


Cannii . 28. 




puscles, 81. 


Capillaries, 87. 




( '< trpuscles and germs, 101. 






264 



INDEX 



Corrosive sublimate, 29, 253. 

Cranium, 37. 

Creosote, 30. 

Cysterna chyli, 90. 

Deafness, 216. 

Decay, 28. 

Dendrites, 65. 

Dermis, 188. 

Diabetes, 200. 

Diaphragm, 118. 

Diet, 137, 138. 

Digestive tract, 160, 248, 251. 

activities, 160. 
Digestion, 159. 

intestinal, 177. 
Diphtheria, 223, 227, 231. 
Disease, 238. 

duration of, 228. 

infectious, 223. 
Disinfect, 253, 254. 
Dislocation, 45. 
Distilled liquors, 146. 
Doctors, 238. 
Drinking water, 259. 
Drugs, 128, 140, 181, 238. 
Dust in breathing, 116, 124, 125. 
Ear, 212. 
Education, 77. 
Emulsion, 183. 
Energy, 17, 18. 
Enzymes, 160. 
Epidermis, 187. 
Epiglottis, 112. 
Epithelium, 115. 
Esophagus, 112. 
Eustachian tube, ill. 
Eye, 203. 
Exercise, 57. 
Fats, 131, 183. 
Feet, 46. 

Fibers, muscle, 13. 
Fibrin, 84. 
Flies, 257, 259. 
Fluids of the body, 14. 
Focus, in sight, 206, 207. 
Food, 61, 129, 257. 

classes of, 130. 

tests, 132. 
Formaline, 29, 253, 254, 255. 
Fracture, 41. 
Fumigation, 254. 



Ganglion, 65. 

Gastric juice, 170. 

Germs, 24, 223, 248. 

Gin, 147. 

Glottis, in. 

Glycogen, 185, 200. 

Goitre, 200. 

Growth, 16. 

Habit, 76. 

Hair, 188, 191. 

Haynes' solution, 132. 

Headache powders, 155. 

Hearing, 212. 

Heart, 103. 

Heat, 57, 59- 

Hemoglobin, 82. 

Humerus, 33, 36. 

Hydrochloric acid, 38. 

Hydrophobia, 228, 230. 

Hygiene, defined, 11. 

Incubation, 228. 

Infundibulum, 116, 117. 

Inorganic foods, 133. 

Intercellular materials, 13. 

Internal secretions, 199. 

Iodine test, 132. 

Iris, 204. 

Joints, 43. 

Kidney, 197. 

Koumis, 145. 

Lacteals, 90, 183. 

Larynx, in, 113. 

Laudanum, 152. 

Ligaments, 44. 

Light, 261. 

Liqueurs, 147. 

Liquors, fermented, 144. 

Liver, 185. 

Lobule of the lung, 116, 117. 

Lockjaw, 223, 232. 

Lungs, 114. 

lobules of, 116, 117. 
Lymph, 14, 81, 84. 
Lymphatics, 84, 85, 89. 
Lysol, 253, 254. 
Malaria, 223, 256. 
Malt, 145. 
Maltose, 165. 
Medicine, 236, 240. 
Medulla, 68, 69, 70. 
Meningitis, 223, 250. 



INDEX 



26s 



Mercury bichloride, 29, 253. 
Mesentery, 108. 
Microbes, 24. 
Micro-organisms, 24. 

Mitral valve, 104. 
Morphine. [52. 
Mosquitoes, 256. 
Motor Nerve, 07. 73- 
Mouth anatomy, 161. 
Mucous membrane, 115. 
Muscles. 40. 

classes of, 54. 
Xails. [92. 
Narcotics, 77. 140. 
Nerve system, 63. 

control. 55. 
Nerves, 65. 

of heart, 106. 

vaso motor. 102. 
Neuraxon, 65. 
Neuron, 64. 
Nicotine. 154. 
Nitrogenous food, 130. 
Nucleus, 12. 
Oils. 131. 
Omentum, 168. 
Opium. 152. 
Op-onin-. 22?. 
Oxidation, 17, 19. 
Oxygen. 121. 

in blood, 108. 

in air, 121. 
Pancreas. 169, 178, 200. 
Parasite. 31. 
Pasteurization, j 75. 
Patent medicines, 245. 
Pelvic girdle, ^. 
Pepsin, 170. 
Pericardium, 104. 
Perimysium, 54. 
Periosteum. 35, 39. 
Peritoneum. 

Perspiration. 188, 100, 195. 
Peristalsis, ly 
Pharynx. 110, l6l. 
Physicians, 243. 
Ph) - lefinition, 1 1. 

Plasmodia, 25 
Play, 60. 

Pneumonia, 124, 223 



Portal vein, 06, 98. 
Preserving food, 28. 
Protei, 134. 

Protoplasm. 15. 

activities of, 16. 

irritability of, 16. 

needs of, 20. 

waste by oxidation, 17, 21. 56. 
Ptomaines, 174, 258. 
Pulse, 105. 
Pus, 31. 

Quarantine, 255. 
Quinine, 236, 240. 
Rabies, 228, 230. 
Rachitis. 42. 

Recurrence of disease, 229. 
Reflex action, 67. 
Rennin, 170. 

Resistance to germs, 224. 
Respiration, 58, 108. 
Retina, 204, 205. 
Rickets, 42. 
Ringworm, 2^7 . 
Rum, 147. 
Sacrum, ^, 36. 
Saint Vitus dance, 79. 
Saliva, 165. 

Salt, a preservative. 30. 
Sanitation, 247. 248. 
Scapula, S3' 36. 
Scarlet fever, 228, 229. 
Sclerotic coat, 203. 
Sebaceous glands, 188. 
Semilunar valves, 104. 
Senses, special, 201. 
Sense organs. 203. 212, 216. 218. 

220, 221. 
Serous membrane. 104, t 1 5. 
Shivering. 57. 194. 
Shoes, 46, 47. 
Shoulder girdle, 35. 
Sight, 203. 
Skeleton, ^.^- 
Skin. 1S7. 249, 2\2. 
Skull. 17- 
Sleep, 70. 
Smallpox. 22^. 
Smell, sense of, 216. 
Smoke. 30. 
Solar plexus, 75. 70. 

Special senses, 201. 



266 



INDEX 



Spinal cord, 73. 
Spectacles, 208. 
Spleen, 201. 
Sprain, 45. 
Stimulants, 77, 140. 
Stomach, 169. 
Stye, 210. 

Subcutaneous, 188, 189. 
Suprareval gland, 199. 
Sulphur, 29, 254. 
Swallowing, 167. 
Sweat, 188, 190, 195. 
Sympathetic nerves, 75. 
Synovium, 44, 116. 
Tannin, 143. 
Tapeworm, 173. 
Taste, 166, 218. 
Tea, 142. 
Teeth, 162. 

classes of, 163. 

care of, 164. 
Temperature, 21, 193. 
Temperature sense, 221. 
Tetanus, 223, 232. 
Theobromine, 144. 
Thoracic dust, 90. 
Thyroid, 200. 
Tissue, 12. 
Tobacco, 153, 176. 



Tongue, 166. 

Tonsils, no. 

Touch, sense of, 220. 

Toxin, 224. 

Trachea, 112, 114. 

Triceps, 50, 53. 

Trichina, 173. 

Tricuspid, 104. 

Tuberculosis, 40, 223, 233. 

Typhoid, 223. 

Urea, 186, 197. 

Uvula, 161. 

Vaccination, 229. 

Vaccines, 226. 

Valves, in heart, 104. 

in veins, 88. 
Veins, 88. 

Ventilation, 121, 125. 
Ventricles, 103. 
Vertebra, 33, 34, 37- 
Vescicle of lung, 117. 
Villi, 182. 

Vitreous humor, 205. 
Voluntary action, 67. 
Water, need of, 21. 
Whiskey, 147. 
Wine, 144. 
Yeast, 25. 
Yellow fever, 256. 



